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MARINE  ENGINES: 


PROBLEMS,   NOTES  AND  SKETCHES. 


ADDITIONAL    TO    THE    TEXT-BOOK    USED    IN    THE    INSTRUCTION 

OF     NAVAL     CADETS     OF     THE     SECOND     CLASS, 

UNITED    STATES    NAVAL    ACADEMY. 


SECOND  EDITION. 


DEPARTMENT    OF    STEAM    ENGINEERING, 

U.    S.    NAVAL    ACADEMY, 

ANNAPOLIS,    MD. 

1899. 


Z-^i  jfrtebenroafb  Company 

BALTIMORE,  MD.,  U,  S.  A. 


Library 

1    ^'^^ 


PREFACE. 

The  following  Problems,  Notes  and  Sketches  have  been  pre- 
pared for  use  in  the  instruction  of  the  naval  cadets  of  the  second 
class. 

The  arrangement  of  the  subjects  treated  follows  that  of  the 
text-book  on  Marine  Engines,  in  order  that  the  books  may  be 
used  conjointly. 

The  book  is  an  outcome  of  a  quantity  of  type-written  matter 
which  was  prepared  originally  by  Passed  Assistant  Engineers  W. 
F.  Worthington  and  John  L.^Gow,  U.  S.  N.,  while  attached  to 
this  school.  With  this  has  been  incorporated  much  new  matter, 
especial  care  having  been  taken  to  explain  the  uses  and  action 
of  boiler  and  engine  attachments  and  patented  devices  met  with 
on  board  ship,  in  order  that  the  cadet  may  obtain  a  thorough 
knowledge  of  the  details  of  marine  machinery,  as  well  as  a  gen- 
eral understanding  of  the  subject. 

The  "Arrangement  of  Machinery,"  and  many  of  the  devices 
mentioned,  are  those  of  the  U.  S.  S.  Bancroft,  one  of  the  Naval 
Academy  practice  ships,  although  not  confined  exclusively  to 
that  vessel. 

Our  thanks  are  due  to  Engineer-in-Chief  Geo.  W.  Melville, 
U.  S.  N.,  Chief  of  the  Bureau  of  Steam  Engineering.  Navy  De- 
partment, by  whose  order  many  of  the  drawings  for  the  book 
were  made  in  that  bureau. 

We  are  indebted  also  to  the  following  named  firms  and  indi- 
viduals for  the  loan  of  electrotypes  of  their  specialties,  and  for 
unvarying  courtesy  in  supplying  all  needful  information,  viz.: 

American  Ship  Windlass  Co.,  Ashcroft  Manufacturing  Co., 
Ashley  Engineering  Works,  R.  Beresford,  Geo.  F.  Blake  Manu- 
facturing Co.,  A.  &  F.  Brow^n.  Chapman  Valve  Manufacturing 
Co..  M.  T.  Davidson,  Detroit  Lubricator  Co..  D'Este  &  Seeley 
Co.,  Goubert  Manufacturing  Co.,  L.  Katzenstein  &  Co..  Man- 
ning, Maxwell  &  Moore,  Nason  Manufacturing  Co.,  South wark 
Foundry  and  Machine  Co.,  R.  F.  Sturtevant  &  Co.,  The  Con- 
solidated Safetv  Valve  Co.,  The  Eaton.  Cole  &  Burnham  Co., 


4  PREFACE. 

The  Lunkenheimer  Co.,  Williamson  Bros.,  and  Henry  R.  Worth- 
ington. 

The  labor  of  preparing  the  book  has  fallen  upon  the  instructors 
in  this  department,  Passed  Assistant  Engineers  F.  W.  Bartlett 
and  L.  D.  Miner,  and  Assistant  Engineers  H.  W.  Jones  and  H, 
O.  Stickney,  U.  S.  N.;  to  Mr.  Jones,  however,  is  due  the  credit 
for  the  greater  part  of  the  work. 

C.  W.  Rae, 

Chief  Engineer,  U.  S.  N.,  Head  of  Department  of  Steam  Engineering. 

U.  S.  Naval  Academy, 

Annapolis,  Md.,  Feb.  i,  1895. 


PREFACE  TO  SECOND  EDITION. 

The  first  edition  of  this  work  having  been  exhausted,  the  pres- 
ent edition  has  been  prepared  to  correspond  with  the  present 
text-book,  "  The  Marine  Steam  Engine,"  by  R.  Sennett  and  H. 
J.  Oram,  which  contains  considerable  matter  that  was  in  the 
first  edition,  and  therefore  can  now  be  omitted.  The  removal 
of  the  "  Bancroft "  from  this  Station  also  allows  the  omission  of 
all  reference  to  the  machinery  of  that  vessel. 

Brief  notes  have  been  added  on  steam  turbines  and  liquid  fuel; 
also,  some  directions  about  care  and  management  of  machinery 
afloat. 

The  notes  on  the  Zeuner  Diagram  have  been  re-written  and 
the  notes  on  the  Steam  Turbine  compiled  by  P.  A.  Engineer 
U.  T.  Holmes,  U.  S.  N.  The  other  additional  matter  has  been 
compiled  from  notes  used  in  the  instruction  of  cadets  in  this 
department. 

The  matter  and  problems  in  this  edition  are  arranged  to  cor- 
respond with  the  arrangement  of  similar  subjects  in  Sennett  and 
Oram. 

Geo.  H.  Kearny, 

Chief  Engineer,  U.   S.  N.,  Head  of  Department  of  Steam  Engineering. 

U.  S.  Naval  Academy,  November,  1898. 


MARINE  ENGINES. 


ART.  I.— (P.  28,  S.  &  O.) 

To  find  the  total  heat  necessary  to  evaporate  one  pound  of 
water  from  a  temperature  of  32°  to  steam  of  t°,  we  have 

H  =  966  —  .7  X  (t°  —  212°)  -f  (t°  —  32°), 

or,  reducing  the  expression. 

H  =  1082  +  .3t°. 

If,  howeveti  we  start  the  evaporation  with  feed  water  of  a 
greater  temperature  than  2^2° ,  or  rather  with  a  temperature  differ- 
ing from  32°,  we  have  already  in  the  water  (calling  the  new  tem- 
perature of  the  feed  t°)  (t^  — 32°)  of  heat  units  which  need  not 
be  supplied  by  the  fuel. 

Therefore  this  amount  of  heat  can  be  subtracted  from  that 
necessary  to  evaporate  the  one  pound  of  water  to  steam  at  the 
temperature  t°  from  feed  of  32°  as  an  origin,  as  found  by  the 
above  formula. 

Calling  the  number  of  heat  units  already  in  the  water  Hp 
taking  32°  F.  as  the  origin, 

H,  =  (t°-32°), 

and  the  heat  to  be  supplied  by  the  fuel 

H  —  H(.  =  1082  +  .3t°  —  (t°  —  32°). 

PROBLEMS  ON  CHAPTERS  III.  and  IV.,  S.  &  O. 

I.  It  has  been  determined  by  experiment  that  the  ratio  of  the 
volumes  of  air,  under  the  same  pressure  at  temperatures  32°  F. 
and  212°  F.,  is  i    :  1.3654.     Assuming  that  air  is  a  perfect  gas, 

PV 

i.  e.  follows  the  law =  a  constant,  find  the  absolute  zero  m 

T 

degrees  Fahrenheit. 


8  MARINE    engines: 

2.  Find  the  total,  latent,  and  sensible  heat  of  steam  of  tem- 
perature 300°. 

3.  Prove,  by  means  of  atomic  weights,  that  12  pounds  of  air 
are,  theoretically,  necessary  for  the  complete  combustion  of  one 
pound  of  carbon.  Assume  the  composition  of  air  to  be  7  parts 
of  N  and  2  parts  of  O. 

4.  Similarly  find  the  number  of  pounds  of  air  necessary  for 
the  complete  combustion  of  i  pound  of  H.       Ajis.     36  pounds. 

5.  Explain  how  the  formula  for  total  heat  of  combustion  is 
derived. 

6.  Find  the  total  heat  of  combustion  and  the  number  of 
pounds  of  air  necessary  for  the  complete  combustion  of  one  pound 
of  coal.  The  analysis  of  the  coal  is  C  =  90  per  cent.,  H  =  8  per 
cent.,  and  O  =  1.2  per  cent. 

Ans.     17921.71  B.  T.  U.,  13.626  pounds  of  air. 

7.  How  many  pounds  of  water  would  a  pound  of  pure  carbon 
evaporate,  theoretically,  if  all  the  heat  of  combustion  of  the  car- 
bon could  be  utiHzed,  the  water  being  at  the  boiling  point  under 
atmospheric  pressure  and  the  pressure  of  the  resulting  steam 
being  also  atmospheric?  In  other  words,  the  evaporation  being 
"  from  and  at  212°  F."  Ans.     15.01  pounds. 

8.  How  many  pounds  of  water  would  the  coal  of  question  6 
theoretically  evaporate  from  and  at  212°  F.?  In  other  words, 
what  is  the  "  evaporative  power  "  of  such  coal? 

Ans.     18.55  pounds. 

9.  How  many  pounds  of  water  would  the  coal  of  question  6 
theoretically  evaporate  if  the  feed  water  be  at  a  temperature  of 
80°  F.,  and  the  resulting  steam  be  at  a  pressure  of  201  pounds 
absolute,  and  have  a  temperature  of  228°  F.? 

Ans.     16.24  pounds. 

10.  How  many  heat  units  are  equivalent  to  i  I.  H.  P.? 

Ans.     42.75  B.  T.  U. 

11.  Suppose  that  all  the  heat  of  combustion  of  pure  carbon 
were  available  for  useful  work,  how  many  pounds  per  I.  H.  P. 
per  hour  would  be  needed?  Ans..     .176  pounds. 

12.  The  best  results  from  modern  engines  show  that  1.5 
pounds  of  coal  per  I.  H.  P.  per  hour  are  needed.     Comparing 


PROBLEMS,  NOTES  AND  SKETCHES.  9 

this  result  with  that  obtained  from  the  combustion  of  pure  carbon, 
what  is  the  efificienc)'  of  the  modern  engine  and  boiler? 

Ans.     II  per  cent. 

13.  A  boiler  uses  the  coal  of  question  6,  and  is  found  to  evapo- 
rate 8  pounds  of  water  per  pound  of  coal  burned.  The  water  fed 
to  the  boiler  has  a  temperature  of  80°  F.  and  the  steam  that  is 
generated  has  a  temperature  of  228°  F.  What  is  the  efficiency 
of  the  boiler?  Ans.     49.7  per  cent. 

14.  Assuming  that  a  boiler  has  an  efficiency  of  65  per  cent., 
burns  1000  povmds  of  coal  per  hour,  and  is  fed  with  water  having 
a  temperature  of  75°  F.,  what  is  the  total  w^eight  of  water  evapo- 
rated per  hour  to  steam  having  a  temperature  of  300°  F.?  An 
analysis  of  the  coal  gives  C  =  91.5  per  cent.,  H  =  3.5  per  cent., 
and  O  =  2.6  per  cent.     The  ash  may  be  neglected. 

Ans.     8772  pounds. 

15.  The  following  is  a  partial  record  of  the  test  of  a  certain" 
boiler  for  efficiency:  Temperature  of  feed,  80°  F.;  temperature 
of  steam,  300°  F. ;  number  pounds  of  feed  water  used,  8000;  num- 
ber pounds  of  coal  used,  1000.  The  feed  water  was  kept  at  a 
constant  level  in  the  gauge  glass  and  an  analysis  of  the  coal  gave 
its  composition  as  follows:  Carbon  =  90  per  cent.,  hydrogen  = 
8  per  cent.,  and  oxygen  :=  1.2  per  cent.  What  was  the  efficiency 
found  to  be?     The  test  lasted  one  hour? 

Ans.     50.18  per  cent. 

16.  The  temperature  of  the  air  being  100°  F.,  what  should  be 
the  temperature  of  the  gases  discharged  from  the  smoke  pipe  in 
order  that  the  draught  shall  be  best?  Ans.     707.75°. 

17.  A  boiler  is  burning  its  maximum  amount  of  fuel  with 
natural  draught,  and  it  is  found  that  the  temperature  of  the  gases 
discharged  from  the  funnel  is  600°  F.  What  is  the  temperature 
of  the  air  at  the  time?  Ans.     48.3°. 

18.  How  does  cannel  coal  compare  with  pure  carbon  as  a 
fuel,  the  composition  of  the  coal  being  C  =  84  per  cent.,  H  =  5.6 
per  cent.,  and  0  =  8  per  cent.?  Compare  the  amounts  of  air 
necessary  to  burn  the  two  fuels. 

Ans.     4  per  ct.  better  as  a  fuel,  and  requires  2  per  ct.  less  air. 

19.  The  analysis  of  a  coal  gives  C  =  .915,  H  =  .035,  0  = 
.026.     (a)  How  much  air  per  pound  will  be  required  to  burn  it? 


lO  MARINE    engines: 

(b)  How  much  water  will  one  pound  evaporate,  theoretically,  from 
a  temperature  of  120^  F.  to  steam  of  180  pounds  pressure,  the 
temperature  of  steam  of  this  pressure  being  373°  F.?  (c)  If  one 
pound  of  this  fuel,  when  used  in  another  boiler,  evaporated  eight 
pounds  of  water,  what  would  be  the  efificiency  of  this  boiler? 

Ans.     (a)   12.123  pounds  of  air; 

(b)  12-77  pounds  of  water; 

(c)  efficiency,  58  per  cent. 

20.  Mineral  oil  is  by  analysis  .84  C,  .16  H.  Assuming  that 
pure  carbon  represents  a  fair  sample  of  good  coal,  how  will  its 
evaporative  power  compare  with  that  of  the  mineral  oil? 

Ans.     The  coal  has  65  per  ct.  the  evaporative  power  of  the  oil. 

21.  A  ton  of  coal  requires  45  cubic  feet  of  bunker  space  to 
stow  it,  and  the  specific  gravity  of  mineral  oil  is  ,88.  Assuming 
the  average  thermal  value  of  the  coal  to  be  equal  to  that  of  pure 
carbon,  how  much  cargo  space  could  be  saved  if  oil  tanks  were 
fitted  in  a  vessel  which  has  a  bunker  capacity  of  1000  tons? 

Ans.     40  per  cent. 

22.  The  analysis  of  peat,  as  given  by  Rankine,  is  carbon,  58 
per  cent.;  hydrogen,  6  per  cent.;  and  oxygen,  31  per  cent.  Com- 
pare the  evaporative  power  of  peat  with  that  of  pure  carbon  and 
find  how  much  air  is  required  to  burn  one  pound  of  the  peat.  * 

Ans.     As  .67095  :  i. 

7.725  pounds  of  air. 

27,.  A  boiler  using  peat  for  fuel  evaporates  i  ton  of  water  with 
4.5  tons  of  peat.  The  feed  water  is  kept  at  75°  F.,  and  the  pres- 
sure of  the  steam  is  kept  constant  at  25  pounds  absolute.  The 
temperature  of  the  steam  is  240°  F.  What  is  the  efficiency  of 
the  boiler?  Ans.     2.6  per  cent. 

24.  A  boiler  is  tested  for  24  hours  and  during  that  time  burns 
235  pounds  of  coal.  The  feed  has  a  temperature  of  100°  F.  and 
30.4  cubic  feet  of  water  are  evaporated  to  steam  having  a  tem- 
perature of  300°  F. 

The  composition  of  the  coal  is  80  per  cent,  carbon,  10  per  cent, 
hydrogen,  and  6  per  cent,  oxygen,  what  was  the  result  of  the 
test  as  to  efficiency?  Ans.     51  per  cent. 


problems.  notes  and  sketches.  i  i 

Calculation  of  Temperature  of  Furnace. 

In  the  12  pounds  of  air  which  are  theoretically  necessary  for 
the  complete  combustion  of  one  pound  of  carbon,  there  are 
12  X  i  =  9-333  +  pounds  of  N.  Burn  the  i  pound  of  carbon 
with  12  pounds  of  air,  to  COo  and  N,  and  the  result  is  as  follows: 

Heat  t'nits  Exiiended. 

N       9-333  +  »  specific  heat  .244;     9.333  X  -244  =  2.2765 
CO„  3.666  "  "     .217;     3.666  X  .217=    .7942 


13.000  of  mixed  gases 30707 

Consequently  the  heat  units  recjuired  to  raise  the  temperature  of 

the  gases  1°   F.  are  3.0707,  and  the  elevation  in  temperature  of 

14500 

the  gases  above  that  of  the  outside  air  is ==  4723°  F- 

^  3.0707 

25.  By  the  method  given  above,  find  the  temperature  of  com- 
bustion when  the  air  supply  is  just  suflficient  to  burn  one  pound 
of  carbon  to  carbonic  oxide,  the  specific  heat  of  CO  being  .245, 
and  the  value  in  thermal  units  of  one  pound  of  carbon  so  burned 
being  4400. 

Ans.     2573°  F.  above  the  temperature  of  the  air. 

26.  Find  the  temperature  of  combustion  and  the  number  of 
pounds  of  air  necessary  for  the  complete  combustion  of  i  pound 
of  mineral  oil,  its  composition  being  84  per  cent,  carbon  and  16 
per  cent,  hydrogen.  Specific  heat  of  COo  is  .217,  of  N  is  .245,  of 
O  is  .218,  of  air  is  .238,  of  CO  is  .245,  and  of  steam  gas  is  .475. 

Ans.     5073°  F.  above  the  temperature  of  the  air. 
15.84  pounds  of  air  necessary. 

27.  Find  the  temperature  of  combustion  caused  by  burning 
one  pound  of  mineral  oil  with  25  pounds  of  air  having  a  tem- 
perature of  90°  F.  Ans.     3445°  F.,  about. 

28.  Find  the  number  of  pounds  of  air  theoretically  necessary 
for  the  complete  combustion  of  one  pound  of  bituminous  coal,  the 
analysis  of  the  coal  being  90  per  cent.  C,  4  per  cent.  H,  and  2  per 
cent.  O.  The  temperature  of  the  air  being  80°  F.  What  will  be 
the  temperature  of  the  furnace?     Specific  heat  of  ash  =  .20. 

Ans.     12.15  pounds  of  air. 

4868°  F.,  temperature  of  furnace. 


12  MARINE    engines: 

HEAT  AVAILABLE  FOR  STEAM  GENERATION. 

Art.  2.— (P.  39,  S.  &  O.) 

Neglecting  the  heat  lost  by  radiation  from  the  ashpit  and  fur- 
nace front,  it  being  a  very  small  quantity  as  compared  with  that 
carried  off  by  the  chimney  gases,  the  amount  of  the  latter  can  be 
calculated  if  the  temperature  of  the  chimney  gases  be  known; 
then  the  difference  between  the  total  amount  of  heat  generated 
by  the  combustion  of  the  fuel  and  the  amount  carried  off  by  the 
discharged  gases  is  a  close  approximation  to  the  total  amount  of 
heat  available  for  steam  generation. 

Suppose  that  the  combustion  of  i  pound  of  carbon  generates 
14,500  heat  units  when  burned  with  15  pounds  of  air,  and  that 
the  temperature  of  the  escaping  gases  is  600°  F.  The  products 
of  combustion  will  be  3.666  pounds  of  CO„,  .666  pounds  of  O, 
and  11.666  pounds  of  N. 

To  find  the  quantity  of  heat  necessary  to  raise  the  products  of 
combustion  1°  F. : 

Number  of  heat  units  carried  ofif  by  the  CO2  =    3.666  X  •2i7flei',eat'i=    -7957 
"      "        "  "        "        "        O      =      .666  X. 218'"     =    .1453 

"     "        "  "       "        "       N      =  II. 666  X. 244    "     = 


"         "      "        "  "        "        "  .  16.0  lbs.  mixed  gases  =  3.7877 

Since  Z-7^77  heat  imits  are  expended  in  raising  the  mixed  gases 
1°  F.,  this  quantity  must  be  multiplied  by  the  elevation  in  tem- 
perature of  the  gases. 

Supposing  the  temperature  of  the  air  to  be  50°  F.,  the  tempera- 
ture of  the  gases  has  been-  raised  from  50°  F.  to  600°  F.  during 
the  process  of  combustion,  or  the  elevation  of  temperature  =  600° 
—  50°  =  550°,  therefore. 

Heat  units  carried  off  by  the  chimney  gases  in  this  case 

=  37877  X  550  =  2083. 

Heat  vmits  available  for  steam  generation 

=  14500  —  2083  =  12417. 

Problems. 

29.  Assuming  the  thermal  value  of  pure  carbon  to  be  14500, 
find  the  heat  available  for  steam  generation  when  one  pound  of 
carbon  is  burned  with  25  pounds  of  air,  the  temperature  of  the 


PROBLEMS,  NOTES  AND  SKETCHES.  I3 

supplied  air  being  80°  F.,  and  that  of  the  escaping  products  of 
combustion  being  600°  F.      Ans.     11281.2  B.  T.  U.  available. 

30.  How  many  pounds  of  coal  will  be  required  to  evaporate 
450  pounds  of  water  to  steam  having  a  temperature  of  300°  F.? 
The  feed  is  70°  F. 

The  coal  is  composed  of  88  per  cent,  carbon,  4  per  cent,  hydro- 
gen, 6  per  cent,  oxygen,  and  2  per  cent,  ash,  and  is  burned  with 
24  pounds  of  air  per  pound  of  coal.  The  temperature  of  the  air 
is  70°  F.  and  of  the  escaping  gases  570°  F.  Specific  heat  of 
ash  about  .200.  Ans.     43.4  pounds  of  coal. 

31.  A  boiler  having  the  most  favorable  temperature  of  escap- 
ing gases  is  supplied  with  twice  the  amount  of  air  theoretically 
necessary  for  complete  combustion  of  the  fuel. 

The  temperature  of  the  supplied  air  is  80°  F. 

One  pound  of  fuel,  of  the  same  composition  as  that  of  the  pre- 
ceding problem,  evaporates  10  pounds  of  water,  from  a  tempera- 
ture of  feed  of  75°  F.,  to  steam  of  240°  F.  Find  the  efficiency  of 
the  boiler,  and  the  efficiency  of  its  heating  surface. 

Specific  heats  of  the  products  of  combustion  are  as  follows: — ■ 

Ash  =  .200  (about).     O  =  .218    Air  =  .238    Steam  gas  =  475 
CO2  =  .217  N  =  .244    CO  r=  .245 

Ans.     Boiler  efficiency  =  75  per  cent. 

Heating  surface  efficiency  =  98.2  per  cent. 

32.  Using  the  coal  of  problem  30,  it  is  required  tO'  find  the 
number  of  pounds  of  water  evaporated  by  one  pound  of  the  coal, 
the  conditions  being  as  follows: 

Temperature  of  the  feed  water  =  130°  F. 
steam,         =373°  F. 
Efficiency  of  the  boiler,  =  60  per  cent. 

Supposing  that  the  temperature  of  the  escaping  gases  is  that 
most  favorable  for  maximum  combustion;  find  the  efficiency  of 
the  heating  surface  of  the  boiler  under  the  following  conditions: 

Number  of  pounds  of  air  furnished  per  pound 

of  fuel  burned, =^12. 

Temperature  of  supplied  air,         ...       .  =  80°  F. 

Ans.     8.09  pounds  of  water  per  pound  of  coal. 
Efficiency  is  68.5  per  cent. 


14 


15 


l6  MARINE    engines: 

Art.  3.— (Chap.  IV.,  S.  &  O.) 

Figs.  I,  2,  3  and  4  show  the  arrangement  of  furnaces  and  ash- 
pits where  forced  draught  is  used  with  "  closed  ashpits." 

The  furnace  front  is  built  upon  a  semicircular  ribbed  cast  iron 
frame,  upon  which  suitable  lugs  are  cast  through  which  bolts  may 
be  passed  for  securing  the  covering  plates,  and  in  which  various 
passage-ways  are  cast,  through  which  the  entering  air  may  freely 
circulate  about  any  portion  of  the  frame. 

The  inner  side  of  the  frame,  except  the  space  occupied  by  the 
door,  is  covered  with  a  perforated  plate  of  steel,  while  the  outside 
is  covered  with  a  solid  plate  which  is  bolted  to  the  frame  and  the 
inner  plate.  This  outer  plate  is  carried  down  below  the  frame- 
work, and  to  it  is  bolted  an  inclined  rectangular  structure  upon 
which  an  airtight  door  may  be  secured  by  the  bolts  s,  and  the  ash- 
pit, or  bottom  half  of  the  furnace,  be  thus  shut  o&  from  the  outer 
air.  To  the  outer  plate  are  secured  lugs  for  the  hinges  and  latch 
of  the  furnace  door. 

The  furnace  door  is  built  up  of  an  outer  sheet  of  steel,  its  edge 
flanged  so  that  it  will  fit  tightly  against  the  furnace  front;  and  to 
this  outer  sheet  is  bolted  an  inner  perforated  sheet  of  such  a  size 
and  shape  that  it  will  easily  enter  the  opening  in  the  casting  as 
the  door  is  swung  to  and  fro.  This  inner  sheet  is  secured  by 
long  bolts,  which  run  through  a  piece  of  pipe,  this  pipe,  with  the 
bolt,  serving  to  hold  the  liner  rigidly  a  distance  of  three  or 
four  inches  from  the  outer  plate,  thus  allowing  the  air  to  circulate 
between  the  inner  and  outer  plates,  the  easily  renewable  liner  and 
the  non-conducting  air  protecting  the  door  from  destruction  and 
partially  preventing  radiation. 

The  latch  and  hinges  are  made  fast  to  the  door  and  the  rod  k 
is  added  to  prevent  the  door  from  sagging  on  its  hinges. 

In  the  bottom  of  the  outer  and  inner  door-plates  an  opening  is 
cut,  and  this  opening  is  closed  on  the  outer  door  by  means  of  a 
plate  swinging  on  horizontal  hinges  and  kept  shut  by  gravity. 
Through  this  opening  a  bar  can  be  run  and  the  clinkers  can  be 
lifted  from  the  grates,  or,  technically  speaking,  the  fires  can  be 
sliced  with  the  slice  bar. 

In  this  method  the  furnace  door  and  ashpit  are  tightly  closed, 
and  fans,  rotating  at  high  speed,  compress  air  to  a  pressure  of  a 
small  fraction  of  a  pound  per  square  inch,  and  force  it  through 
channel-ways   or   air   ducts   to  the   ashpit.     These   channel-ways 


PROBLEMS,  NOTES  AND  SKETCHES. 


17 


may  be  led  across  the  front  of  the  boiler,  where  the  air  is  par- 
tially heated,  and  down  to  the  ashpits,  where  it  is  discharged;  or 
they  may  be  led  to  the  floor  plates  of  the  fire-room  and  under 
these  to  the  ashpit  as  before. 

The  amount  of  air  sup- 
plied can  be  regulated  by 
varying  the  speed  of  the 
blowers,  and  it  can  also  be 
controlled  by  a  damper 
placed  in  the  duct. 

The  ashpit  is  closed  by  a 
rectangular  door  fitted  to 
make  an  airtight  joint,  and 
held  in  place  by  bolts,  s,  s, 
as  shown  in  Fig.  i. 

Fig.  3  shows  the  method 
of  making  the  joint  of  this 
door  so  that  it  may  be  tight 
enough  to  prevent  the  escape 
of  the  air  under  its  light  pres- 
sure. 

To  the  inner  side  of  the 
steel  plate  are  fastened,  by 
small  screws,  two  light  rectangular  steel  frames,  t,  t,  one  slightly 
larger  than  the  other.  These  frames  serve  to  form  a  channel- 
way  in  which  the  edge  of  the  ashpit  box  u  just  fits  and  prevent 
the  door  frame  sHding  down  when  in  place.  They  also  hold  in 
place  strips  of  asbestos  sheeting,  this  last  forming  an  elastic  non- 
combustible  packing  which  efifectually  seals  the  joint  when  the 
bolts  are  shot  in  place. 

To  the  right  of  the  door  is  shown  a  section  of  the  damper 
spindle  with  a  sectional  portion  of  the  damper  attached. 

With  the  blowers  running  and  all  the  furnace  doors  and  ashpit 
doors  closed  the  pressure  of  the  air  and  hot  gases  in  the  furnaces 
nearly  equals  that  of  the  air  in  the  ducts,  and  should  a  furnace 
door  be  suddenly  opened,  without  first  shutting  off  the  damper 
of  the  air  duct  to  the  ashpit  of  that  furnace,  the  hot  gases  would 
rush  from  the  furnace  through  its  door  into  the  fire-room.  Many 
serious  accidents  have  happened  in  this  way,  and  it  is  to  save 
the  firemen  from  the  results  of  his  own  thoughtlessness  that  the 
mechanism  shown  in  Fig.  4  has  been  added  to  the  doors  of  many 


Fig.  3.— Method  of  Packiug 
Ashpit  Door. 


i8 


MARINE    engines: 


furnaces  in  which  combustion  is  aided  by  the  Closed  Ashpit  System 
of  forced  draught. 

It  will  be  seen  that  the  mechanism  consists  of  a  handle  m  piv- 
oted at  one  extremity  to  a  slotted  plate,  bolted  to  the  furnace 

front,  and  having  a  curved  arm 
x  in  one  with  it  on  its  upper 
edge,  while  on  the  lower  edge  is 
a  lug  fitted  with  a  bolt  which 
passes  through  the  slotted  plate. 
The  bolt  is  fitted  with  a  handled 
nut  w  (see  Fig.  i),  by  means  of 
which  the  handle  can  be  clamped 
at  any  point  of  its  travel  along 
the  slot.  To  the  other  extremity 
of  the  bolt  is  made  fast  a  rod  p 
(see  Fig.  i),  the  other  end  of 
which  is  connected  with  a  crank 
on  the  end  of  the  damper 
spindle. 

In  the  position  of  the  handle 
shown,  the  curved  arm  x  is  over 
the  door  latch  /  (also  see  Fig.  2), 
and  until  tn  be  swung  down  carrying  x  with  it,  the  door  latch  / 
cannot  be  raised  from  its  hook,  and  consequently  the  door  cannot 
be  opened. 

Should  the  fireman  wish  to  open  the  door,  he  must  unclamp 
and  push  down  the  lever  m,  and  must  push  it  down  so  far  that 
the  end  of  x  wdll  clear  the  latch  /,  and  this  will  bring  the  handle 
ni  into  the  new-  position  n.  But  w^hen  the  handle  m  is  shoved 
down,  the  rod  p  (see  Fig.  i),  is  carried  down  too,  and  as  it  goes 
dow^n  it  turns  the  crank  on  the  damper  spindle,  and  so  closes  the 
damper  and  shuts  off  the  air.  The  position  of  the  damper  when 
closed  is  shown  in  Figs.  2  and  3. 

It  can  now  be  seen  that  if  the  fireman  wishes  to  open  the  door 
of  the  furnace,  to  do  so  he  is  forced  to  first  close  the  damper, 
thus  relieving  the  gases  of  the  additional  pressure,  when  he  may 
raise  the  latch  and  open  the  door. 


Fij 


4. — Side  Elevation  of  Furnace 
Door  Locking  Device. 


PROBLEMS,  NOTES  AND  SKETCHES.  I9 

NOTES  ON  LIQUID  FUEL. 

Art.  4.— Chap.  VI.,  S.  &  O.) 

Liquid  Fuel — Gives  special  facilities  for  the  development  and 
maintenance  of  intense  heat,  for  the  quick  control  of  applied, 
steady  heat,  and  for  the  rapid  generation  of  steam.  Liquid  fuels, 
such  as  petroleum,  petroleum  residue,  tar,  and  creosote-oil  have 
a  much  higher  calorific  power  than  coal,  because  they  contain  a 
much  larger  quantity  of  hydrogen.  Petroleum  is  a  natural 
hydro  carbon  oil,  having  in  its  crude  state  a  calorific  power  one 
and  one-half  times  as  great  as  that  of  coal.  Petroleum  oil  is 
obtained  by  distillation  from  petroleum.  Its  calorific  power  is 
from  two  and  one-half  to  three  times  that  of  coal.  The  best  pe- 
troleum fuel  oil  has  a  specific  gravity  of  0.818.  Its  composition 
averages  as  follows:  Carbon,  85.34:  Hydrogen,  13.51;  Oxygen 
and  impurities,  1.15.  It  contains  about  three  times  as  much 
hydrogen  as  is  contained  in  good  coal.  The  theoretical  heating 
power  of  this  fuel  is  20,822  thermal  units,  and  it  has  a  theoretical 

20822 

evaporative  power  of =21.56  lbs.  of  water,  from  and  at 

966 

212°  F.  per  lb.  of  oil.  Its  actual  evaporative  power  in  practice 
is  from  15J/2  to  17  lbs.  of  water.  Its  flashing  point  is  about  217° 
F.  In  a  general  way  104  gallons  or  851  lbs.  of  this  oil  are  equal 
to  one  ton  of  good  coal  in  evaporative  power.  Petroleum  fuel  is 
burned  in  a  furnace  in  the  form  of  spray  after  having  been  pul- 
verized or  atomized  by  steam  or  compressed  air  or  both.  An 
ordinary  furnace  can  be  used  for  burning  fuel  oil,  but  a  large 
quantity  of  smoke  is  formed  and  the  heating  surface  becomes 
coated  with  a  sticky  non-conducting  substance.  Better  results 
are  obtained  by  lining  the  furnace  with  fire-brick  when  the  high 
temperature  prevents  the  cooling  of  the  gases  and  the  partial 
extinction  of  the  flame.  When  the  oil  is  sprayed  into  a  furnace 
of  this  kind  and  a  large  quantity  of  air  is  supplied,  practically 
complete  combustion  may  be  obtained  with  no  soot. 

Air  Required. — The  air  required  for  the  complete  combus- 
tion of  fuel  oil  is  at  least  one-third  greater  than  that  required  for 
coal  of  good  quality.  The  minimum  quantity  of  air  that  should 
be  provided  in  practice  is  22  lbs.  of  air  per  lb.  of  oil,  but  it  is 
generally  necessary  to  provide  a  larger  amount  than  this  to  pre- 
vent smoke. 


20  MARINE    engines: 

Comparison  of  Coal  and  Oil  for  Composition  and  Theo- 
retical Evaporation. 


i:  o  rS 


■  C3 


Spec.  grav.  *"=  --ii 

at  3;'.  C.  11.  ().  -  c-  — 

Penna.  heavy  crude  oil 886  84.9  13.7  1.4  20736  21.48 

Caucasian        "        "     938  86.6  12.3  i.i  20138  20.85 

Petroleum  residue 938  87.1  11. 7  1.2  19832  20.53 

Good  English  coal 1.380  80.0  5.0  8.0  141 12  14.61 

Boiler  using  Liquid  Fuel. — As  a  boiler  well  equipped  for 
the  combustion  of  liquid  fuel  should  produce  no  soot,  the  tube 
may  be  of  small  diameter  and  the  heating  surface  may  thus  be 
increased  from  33  per  cent,  to  50  per  cent. 

Petroleum  Residue  or  Astaki. — This  is  the  hquid  fuel  gen- 
erally used  and  is  the  dead  oil  or  residue  left  in  the  still  after 
the  crude  oil  has  been  refined.  It  makes  an  excellent  fuel  for 
boilers.  The  flashing  point  is  about  212°  F.  The  theoretical 
evaporation  is  17.1  lbs.  of  water  per  lb.  of  fuel.  The  actual  evapo- 
rative value  is  found  to  be  14  lbs.  or  82  per  cent,  of  the  theo- 
retical efficiency. 

The  Working  of  Oil  Fuel  Apparatus  on  Board  Ship. 

With  petroleum  fuel  the  regulation  of  the  fires  is  very  simple: 
the  only  thing  of  importance  to  be  observed  is  to  adjust  the  regu- 
lating valves  of  the  pulverizers  and  the  air  doors  of  the  furnaces 
in  such  a  way  as  to  get  a  brilliant  white  flame  throughout  the 
furnace,  entirely  free  from  reddish,  bluish,  or  yellowish  striae,  in 
order  to  ensure  perfect  combustion.  Perfect  combustion  is  nec- 
essary not  only  for  the  economy  of  fuel  but  also  for  preventing 
the  formation  of  smoke  or  a  second  combustion  taking  place  in 
the  uptakes,  which  frequently  happens.  When  the  fires  are  well 
regulated  the  firemen  have  nothing  to  do  except  to  watch  the 
water  level  in  the  boilers  and  the  level  in  the  oil-feeding  tank. 
One  man  can  look  after  many  boilers  and  a  great  saving  in  labor 
can  be  effected.  Other  advantages  not  to  be  disregarded  are  the 
great  uniformity  of  fire  and  consequently  of  steaming;  the  easy 
regulation  of  the  boilers;  and  the  cleanliness  that  obtains  in  the 
fireroom,  on  account  of  the  total  absence  of  coal  and  ashes.     As 


PROBLEMS,  NOTES  AND  SKETCHES.  21 

the  oil  fuel  is  very  dense,  to  make  it  more  fluid,  it  is  usual  to  heat 
it  in  the  feeding  tank  with  steam  through  a  steam  coil. 

Heating  the  oil  has  also  the  advantage  of  improving  com- 
bustion and  diminishing  the  expenditure  of  steam  in  the  pulver- 
izer. To  prevent  sediment  finding  its  way  into  the  oil-feeder 
tank  the  latter  is  fitted  with  a  strainer  through  which  the  oil 
pumped  through  the  main  reservoirs  is  made  to  pass.  The  oil 
reservoirs  on  board  ship,  which  in  men-of-war  ought  always  to 
be  built  below  the  waterline,  may  be  kept  with  the  oil  at  a  free 
level  which  falls  as  the  oil  is  pumped  out;  or  it  may  be  kept  full. 
In  the  latter  case  the  reservoirs  are  put  in  direct  communication 
at  the  bottom  with  the  sea,  and  the  oil  is  pumped  out  at  the  top 
as  required.  This  arrangement  has  the  advantage  that  the  oil 
being  kept  steady  and  being  taken  from  the  top  is  freer  from 
sediment,  while  the  conditions  of  trim  and  stability  of  the  ship 
are  left  unaltered.  The  water  being  heavier  rests  at  the  bottom 
and  there  is  no  danger  of  its  mixing  with  the  oil.  Air-pipes  are 
always  fitted  to  the  tops  of  the  reservoirs  for  the  free  exit  of  gases 
and  entrance  of  air.  Whether  kept  full  or  at  a  free  level  the  oil 
reservoirs  are  not  dangerous  because  the  naphtha  refuse  left  as 
waste  in  the  refining  works  after  the  illuminating  oils  and  lubri- 
cating oils  have  been  distilled  has  a  very  high  burning  point, 
which  is  above  200°  C.  Sometimes,  however,  a  refuse  with  a 
high  burning  point  may  be  mixed  with  another  of  a  more  vola- 
tile nature  which  has  been  left  as  waste  after  the  illuminating  oils 
only  have  been  distilled;  and  sometimes  crude  petroleum  itself, 
with  all  the  volatile  oil,  is  mixed  with  the  refuse.  In  these  cases 
of  mixture  there  may  be  danger.  It  is,  therefore,  of  the  utmost 
importance  that  the  oil  fuel  be  tested,  to  ascertain  that  it  is  free 
from  vapors  and  light  oils,  and  that  it  has  a  high  burning  point, 
at  least  130°  C.  before  it  is  received  on  board. 

Use  of  Coal  and  Oil  Fuel  Combined. — This  is  effected  by 
working  a  coal  fire  oh  an  ordinary  grate  and  admitting  the  oil  fuel 
through  holes  above  the  furnace  door,  leaving  the  door  free  for 
coal  firing.  When  using  the  two  fuels  combined,  care  must  be 
taken  to  allow  air  to  enter  in  sufficient  quantities  inside  the  fur- 
nace above  the  fire-grate  in  order  to  insure  perfect  combustion. 
Failing  this,  combustion  may  take  place  in  the  smoke  box  and 
funnel.  This  is  prevented  by  leaving  the  grate  barely  covered  in 
front  near  the  fire  door.  With  the  combined  fuels  in  ordinary 
marine  furnaces  the  flame  is  not  so  white  as  with  liquid  fuel  alone, 


22  MARINE    ENGINES: 

burning  inside  a  fire-brick  chamber.  The  proportions  of  fuels 
used,  one  of  oil  fuel  to  five  of  coal,  appear  the  most  convenient 
to  secure  power  combined  with  efficiency.  When  using  the 
combined  fuels  it  is  necessary  for  perfect  combustion  to  work 
the  coal  fire  as  regularly  as  possible,  just  as  when  using  coal 
alone;  but,  in  the  former  case,  the  rush  of  cold  air  through  the 
furnace  doors  when  firing  is  not  so  detrimental  as  with  coal  alone, 
the  cold  air  always  finding  in  the  furnace  above  the  grate  a  large 
quantity  of  hydrocarbon  vapors  with  which  it  must  mingle  be- 
fore reaching  the  tube  plates.  An  important  feature  of  the  use 
of  liquid  fuel  with  coal  lies  in  the  readiness  and  ease  with  which 
the  full  power  of  the  boilers  can  be  obtained  by  a  simple  turn  of 
a  handle. 

Experimental  Data  and  Conclusions. 

From  experiments  in  the  Italian  navy  the  following  are  ob- 
tained: The  heating  power  of  petroleum  refuse  compared  with 
that  of  coal  is  at  least  1.44,  reckoned  from  the  weight  of  water 
evaporated  per  equal  weight  of  fuel.  It  is  found  that  when  using 
both  fuels  the  power  obtained  under  the  same  conditions  is  in- 
creased ten  per  cent,  over  that  obtained  with  coal  alone,  and  that 
the  calorific  power  of  oil  fuel  used  in  this  way  is  1.55  times  that  of 
coal.  The  fuels  used  per  I.  H.  P.  are  about  1.21  lbs.  of  coal  and 
0.31  lbs.  of  oil,  making  a  total  of  1.50  lbs.  per  I.  H.  P.  burned  to- 
gether and  about  1.71  lbs.  of  coal  per  I.  H.  P.  used  alone. 

The  conclusions  arrived  at  in  the  Italian  navy  are  as  follows: 

1.  Petroleum  refuse  seems  to  be  the  marine  fuel  par  excellence. 

2.  At  present  on  account  of  the  high  price  and  the  small  quantity 
available,  notwithstanding  the  many  advantages  that  may  be  de- 
rived from  it,  petroleum  refuse  cannot  be  adopted  for  general 
use  on  board  ship,  at  least  in  the  mercantile  navy.  In  war  ships 
its  military  advantages  may  lead  even  now  to  its  partial  adoption. 

3.  The  use  of  coal  and  oil  fuel  combined  gives  an  easy  and  safe 
way  of  using  the  greater  power  of  oil  without  dispensing  with 
the  coal  arrangements.  4.  For  torpedo  boats  requiring  small 
fuel  carrying  capacity  and  steaming  short  distances  oil  fuel  can 
now  be  used  to  advantage. 

The  following  are  the  objections  to  the  use  of  liquid  fuel  in 
naval  vessels:  i.  Even  with  the  utmost  care  a  certain  amount 
of  volatile  substance  is  sure  to  be  mixed  with  the  refuse  burned 
and  the  intense  heat  of  the  upper  parts  of  the  fire-rooms  in  naval 


PROBLEMS,  NOTES  AND  SKETCHES.  23 

vessels  is  a  certain  cause  of  danger;  the  fuel  quickly  developing 
the  generation  of  gases  which  increase  as  combustion  is  forced. 
The  accumulation  of  gases  goes  on  continually  and  is  invariably 
present  in  any  existing  space  and  is  apt  to  explode  whenever 
heat  and  air  strike  it.  2.  Oil  penetrates  the  riveted  seams  and 
rapidly  deteriorates  the  rivets  of  the  oil  reservoirs  and  would 
have  the  same  effect  on  the  metal  of  the  double  bottoms  (which 
would  probably  be  used  as  the  reservoirs)  in  naval  ships.  These 
could  not  be  examined  regularly  as  it  takes  a  week  or  more  with 
the  strong  blast  of  a  fan  to  prepare  a  compartment  for  entrance. 
The  examination  would  not  be  satisfactory  as  the  surfaces  are 
covered  with  thick  deposit.  3.  The  odor  has  not  yet  been  over- 
come and  is  very  objectionable.  4.  A  special  objection  is  due 
to  the  fact  that  the  weight  of  water  used  in  the  form  of  steam  for 
burning  the  fuel  is  from  8  to  13  per  cent,  of  all  the  water  evapo- 
rated, which  would  prevent  the  use  of  this  fuel  for  seagoing 
ships  where  there  is  already  such  difficulty  in  keeping  fresh  water 
in  the  boilers. 

WARD'S  LAUNCH  BOILER. 
Art.  5.— (Chap.  VIIL.  S.  &  O.) 

Fig.  5  is  the  type  known  as  Ward's  Launch  Boiler,  and  it  is  in 
use  in  a  number  of  the  launches  in  our  navy.  F  is  a  drum  of 
sheet  steel  with  curved  cast  steel  bottom  head  and  having  a  large 
hand-hole  in  its  top  head.  From  the  bottom  quarter  of  this  drum, 
curved,  spaced  tubes  run  down  and  join  the  lower  annular  drum 
C,  which  curves  vertically  at  G  to  permit  placing  the  door  frame 
and  door  G.  From  the  bottom  of  the  upper  or  steam  drum  F  are 
hanging  tubes  which  are  normal  to  the  curved  plate. 

The  grate  bars  are  supported  by  lugs  on  C  and  a  metal  casing 
covers  and  supports  the  whole,  and  terminates  in  the  stack. 

The  feed  water  is  pumped  into  the  drum  F  and  falls  inside  the 
space  around  the  plate  A,  from  which  it  enters  the  upper  ends  of 
the  vertical  tubes,  as  shown  by  the  arrow,  falls  to  C  and,  rising, 
pours  out  of  the  upper  end  of  the  shorter  vertical  tubes  and  falls 
upon  the  curved  plate. 

The  hanging  tubes  are  seen  to  hold  two  smaller  tubes,  one  pro- 
jecting above  the  curved  plate,  the  other  below  and  into  the  hang- 
ing tube.  The  water  from  the  bottom  of  the  steam  drum  there- 
fore runs  into  h,  and,  with  its  contained  steam  rises  through  c, 


Fig.  5. — Ward's  Launch  Boiler 
24 


26  MARINE    engines: 

the  steam  further  rising  into  F,  from  which  it  is  drawn  for  use, 
while  the  entrained  water  descends  again  through  h  to  be  further 
evaporated. 

The  process  then  is  to  fill  the  space  around  A  with  water. 
Gravity  causes  it  to  descend  in  the  vertical  tube,  and  in  its  de- 
scent it  is  partly  heated  by  the  furnace  gases  which  surround 
these  tubes.  It  fills  C,  is  further  heated  as  it  rises  through  the 
inner  vertical  tube  and  is  discharged,  as  water  and  steam,  into 
the  lower  part  of  the  drum.  The  steam  rises,  while  the  remain- 
ing water  falls,  passes  through  b  to  the  bottom  of  d,  the  hanging 
tube,  and  rises  as  already  described.  The  circulation  is  thus  seen 
to  be  automatic  and  the  water  must  continue  its  circuit  until  it 
shall  all  have  been  evaporated,  other  water  being  meanwhile  sup- 
plied to  A  to  equal  the  amount  evaporated  and  drawn  ofif. 

Towne's  Launch  Boiler. 

Another  type,  also  used  in  some  of  the  steam  launches,  is 
Towne's  Boiler,  shown  in  Fig.  6. 

This  type  combines  a  shell  of  small  volume  with  the  large  tube 
surface  and  the  upper,  or  steam,  drum.  The  shell  encloses  the 
grates  and  the  gases  pass  between  the  inclined  tubes  above  the 
grate  and  pass  out  of  the  funnel  above. 

The  feed  water  enters  a  pipe  coiled  along  the  steam  drum,  and 
the  hot  gases  give  up  some  of  their  heat  to  this  pipe  and  the  con- 
tained water,  before  the  water  is  discharged  into  the  lower  part  of 
the  steam  drum. 

The  feed,  heated  as  explained,  fills  the  lower  part  of  the  drum, 
runs  into  the  dozvii-casf  pipes  C,  enters  the  lower  part  of  the  shell 
and,  rising,  fills  the  tubes  to  the  level  of  the  water  in  the  drum. 
Heat  being  applied,  the  steam  bubbles  rise  along  the  inclined 
tubes  D  and  the  shell,  and  collecting  in  the  top  of  the  shell  are 
discharged  through  the  tubes  B  against  the  deflecting  plates  5'. 
The  entrained  water  falls  to  the  bottom  of  the  drum,  Avhile  the 
liberated  steam  is  drawn  oiT  through  the  perforated  plate  P  and 
the  steam  pipe  H. 

The  feed  continually  entering,  the  circulation  goes  on  con- 
tinuously as  explained. 

Art.  6.— (F.  io6,  S.  &  O.) 

The  safety  valve  shown  in  Figs:  85  and  86  of  Sennett  &  Oram 
is  similar  to  those  used  in  our  navy  except  that  the  springs  and 


PROBLEMS,  NOTES  AND  SKETCHES. 


27 


adjusting  nuts  are  protected  by  a  metal  casing,  and  the  valve  is 
lifted  by  a  lever  acting  on  the  top  of  the  valve  stem.  Fig.  7 
shows  a  valve  and  its  sectional  view.  In  the  navy  two  or  more 
valves  are  often  fitted  in  the  one  casting,  so  as  to  get  the  re- 
quired valve  area  without  having  too  large  a  valve. 

This  valve  has  a  seat  of  solid  nickel  (which  does  not  corrode), 
beveled  at  an  angle  of  45°.  The  valve  is  fitted  with  Richardson's 
adjustable  screw  ring,  by  which  the  closing  pressure  can  be  al- 
tered without  taking  the  valve  apart:  this  is  done  by  removing 
the  small  plug  shown  on  the  right  of  the  sectional  view  and  mov- 


ing the  ring  by  means  of  a  pin,  thus  raising  or  lowering  its  upper 
edge. 

The  valve  is  lifted  by  means  of  the  lever  acting  on  the  loose 
casing  over  the  nuts  at  the  top  of  the  valve  stem,  which  lifts  the 
valve  by  means  of  the  key  fitted  through  the  valve  stem.  This 
key  can  be  secured  by  a  padlock  through  the  hole  shown  in  its 
end,  thus  preventing  any  tampering  wdth  the  adjusting  nuts  after 
once  set.  The  section  of  the  valve  itself,  as  shown,  is  through 
one  of  the  cross  guides  fitted  below  the  valve. 


28 


MARINE    engines: 


SENTINEL  VALVE. 
Art.  7.— (P.  109,  S.  &  O.) 


itD 


Fig.  8. 


The  sentinel  valve,  shown  in  Fig.  8,  will  be  seen  to  be  a  small 
weighted  lever  safety  valve,  with  a  sliding  weight  A,  which  can 
be  changed  to  any  point  on  the  lever  B  by  the  screw  and  hand 
wheel  P. 

The  flange  AI  is  bolted  to  a  pipe  leading  from  the  steam  space,, 
and  the  weight  is  so  set  as  to  exert  a  pressure,  slightly  below 
the  working  pressure  of  the  boiler,  upon  the  valve  f.  The  valve 
will  rise  when  this  pressure  is  reached,  and  the  steam  hissing  from 
the  small  opening  into  the  fire-room  will  call  the  attention  of  the 
water-tender  to  the  increase  in  pressure,  and  warn  him  to  check 
it  before  the  safety  valves  begin  to  blow.  K  and  L  are  guides 
and  supports;  E  and  D  are  hardened  steel  bearing-plates. 

THE  LANE  IMPROVEMENT. 

Art.  8.— (P.  no,  S.  &  O.) 

This  is  an  improvement  on  the  Bourdon  gauge,  shown  on; 
p.  no  of  the  text-book.  The  closed  tube  is  connected  near  its 
middle  to  the  steam  pipe,  the  two  ends  coming  one  above  the 
other  near  the  top  of  the  gauge,  and  the  sector  which  moves  the 
index  is  connected  to  each  end.  This  arrangement  multiplies 
the  motion  and  enables  a  stififer  spring  to  be  used,  thus  increas- 
ing its  durability  and  accuracy  after  long  use.  One  of  these 
gauges  will  be  found  in  the  model  room. 


PROBLEMS,  NOTES  AND  SKETCHES. 


29 


Art.  9.— (P.  Ill,  S.  &  O.) 

It  sometimes  happens  that  the  gauge  glass  breaks  and  steam 
and  hot  water  are  blown  violently  out  into  the  fire-room  until  the 

valves  at  the  top  and  bottom  of  the 
glass  can  be  shut.  As  the  gauges  are 
usually  just  over  the  furnace  doors, 
this  accident  is  liable  to  cause  some 
of  the  firemen  to  be  scalded  unless  the 
valves  can  be  made  to  close  automati- 


Fig. 
water 


Fig.  9. — Kevser's  Automatic 
Water  Gauge  Valve. 


9   is   one   of   these   automatic 
gauge    valves    shown    closed. 
The   valve  wheel  is 
fitted  to  the  square 
end  of  the  stem  and 
the  glass  is  fitted  as 
shown,  the  thread- 
ed end  of  one  valve 
being   fitted   to  the 
pipe    to    the    steam 
space,  the  other  to 
the    pipe   to   water, 
the  glass  being  ver- 
tical and  the  valve 
stems  horizontal,  in- 
stead   of   as    shown 
in  the  figure. 
The  valve  itself  is  conical  and  sepa- 
rate from  the  stem,  and  is  ordinarily 
held  away  from  the  conical  seat  by  a 
light  coiled  spring  fitted  against  the 
crossed  guides.     The  opposite  end  of 
the  valve  is  recessed  in  four  places; 
that  is,  it  has  a  raised  metal  cross  cast 
on  it. 

The  end  of  the  valve  stem  is  conical 
in  its  larger  part,  and  ends  in  a  pin 
which  can  reach  the  separate  valve 
and  force  it  from  its  seat  w^hen  closed. 
The  conical  part  of  the  stem  forms  a 


30 


MARINE    engines: 


second  valve  fitting  to  a  seat  in  the  casting  just  back  of  the 
coiled  spring.  This  valve  is  shown  closed.  If  it  be  opened 
water  or  steam  will  fiow  by  the  larger  and  smaller  valve  into  the 
gauge  glass  and  will  there  be  in  equilibrium.  Should  the  glass 
break  there  is  a  violent  issue  of  steam  or  water,  and  the  larger 
valve  being  carried  along  with  it  compresses  the  coil  spring  and 
seats  itself,  thus  shutting  off  the  flow  automatically. 

The  smaller  valve  can  then  be  safely  closed,  a  new  glass  can  be 
inserted,  the  small  valve  opened  again  and  the  steam  and  water 
readmitted  to  the  glass. 

Art.  ic— (P.  ii6,  S.  &  O.) 

An  oily  scum  may  collect  upon  the  surface  of  the  water  in  the 
boilers,  and  provision  must  be  made  to  get  rid  of  this  by  blowing 
it    overboard.     Fig.     lo    shows    the    method    employed.     The 


Fiif.  10. — Surface  Blow. 

branch  pipe  a  has  angle  valves  fitted  to  each  of  the  flanges  c  and 
h,  and  these  valves  are  flanged  and  bolted  to  the  shells  of  adjacent 
boilers.  From  each  valve  is  led  an  interior  pipe  i  which  ends  in 
a  sciim-pan  just  under  the  surface  of  the  water  near  the  centre  of 
the  boiler. 

The  scum-pan  k  is  sometimes  placed  in  an  inverted  position 
about  four  to  six  inches  above  the  ordinary  water  level  in  the 
boiler. 

Also,  in   place  of  the  scum-pan.   an  open  pipe  or  trough   is 


PROBLEMS,  NOTES  AND  SKETCHES.  3I 

sometimes  fitted  just  below  the  water  level,  extending  around 
the  inside  of  the  boiler,  near  the  shell. 

When  the  valve  d  is  opened,  the  pressure  of  the  steam  forces 
the  water  into  the  scum-pan  and  through  the  valves  and  piping 
overboard;  the  scum  on  the  surface  of  the  water  is  drawn  to  the 
place  of  discharge  and,  as  the  water  becomes  lower,  it  is  gradually 
forced  into  the  pipe  and  overboard  also. 

Art.  II.— (P.  117,  S.  &  O.) 

The  surface  blozv  is  sometimes  used,  though  it  is  best  to  use 
the  bottom  hlozv,  to  reduce  the  saturation  of  the  water,  this  having 
been  previously  found  by  means  of  the  salinometer  shown  in 
Fig.  II.  The  globe  valve  a  is  connected  to  a  pipe  leading  from 
the  water  space  of  the  boiler,  and  when  it  is  opened,  the  water 
rushes  up  the  pipe  b,  the  end  of  which  is  closed  by  a  solid  cap  o, 
and  pours  out  through  the  small  holes  near  its  end.  There  is  a 
channel  d  in  the  bottom  of  c  which  connects  this  chamber  with 
e,  in  which  are  seen  the  thermometer  and  salinometer  or  hydrometer. 
The  water  rises  quietly  to  the  top  of  the  overflow  tube  f  through 
which  the  surplus  amount  escapes  to  the  bilge. 

The  thermometer  being  in  place,  the  water  is  turned  on,  and 
its  temperature  is  allowed  to  rise  to  either  190°,  200°,  or  210°, 
when  the  salinometer  is  put  in  and  the  scale  corresponding  to  the 
temperature  used  is  read  on  the  stem.  The  salinometer  is  kept 
upright  by  the  shot  in  its  lower  end,  and  the  water  having  been 
previously  quieted  in  the  chamber  r,  allows  a  correct  reading  to 
be  made. 

The  scale  of  the  salinometer  used  in  our  navy  is  graduated  to 
represent  the  number  of  pounds  and  quarter  pounds  of  salt  con- 
tained in  thirty-two  pounds  of  the  mixture,  and  the  lengths  of 
the  divisions  of  the  scale  are  calculated  as  follows: 

Let  W  ==  weight  of  i  cu.  in.  of  pure  water. 

W      . 
w  := —  m  mcrease  in  weight  of  i  cu.  in.  of  water,  due  to 
32 

the  addition  of  -jV  of  its  weight  of  salt. 
.-.  IV  +  wx  =:  JV(  I  H j  =  weight  i  cu.  in.  of  water  to  which 

—  of  its  weight  of  salts  have  been  added,  or.  in  other  words, 
32 


Fig.  11  —  Salinometer. 
32 


PROBLEMS,  NOTES  AND  SKETCHES.  33 

the  weight  of  i  cu.  in.  of  water  from  a  boiler  the  density  of  whose 

X 

contents  bv  sahnometer  is  — . 

32 

Let  the  stem  of  the  hydrometer  be  of  uniform  size  and  have  a 
cross  section  of  a  sq.  in.,  and  let  ['  equal  the  volume  in  cu.  ins. 
of  the  immersed  portion  of  the  salinometer  when  floating  in  pure 
water,  then  WV  is  the  weight  of  the  salinometer. 

Let  y  =  the  amount  the  hydrometer  rises  when  floating  in  water 

X 

whose  density  is  —  ;  its  immersed  volume  will  then  be  (F  —  ay). 
This  quantity,  multiplied  by  the  weight  of  i  cu.  in.  of  salt  water 

X 

of  the  density  of  —  will  equal  the  weight  of  the  salinometer;  or 

{V  —  ay)  (IV  +  wx)  =  VW. 

VW  V{        wx        )       V/      X 

■■■   ^  -  ^/ =^-m7XT:7Ta  ;    orj  = 


'{IV+  ivx) '        -^      ~a\[W  -{-  ivx)  )       a\y^  +  X 
From  this  the  different  values  of  3'  can  be  calculated. 

STOP  \' ALVES. 

Art.  12.— (P.  119,  S.  &  O.) 

Valves  similar  to  the  one  shown  in  Fig.  12  have  been  exten- 
sively used  in  some  of  the  later  ships  of  our  navy  in  both  steam 
and  water  pipes.     From  its  form  it  is  called  the  Gate  Valve. 

Owing  to  the  unobstructed  passageway,  when  the  valve  is 
lifted,  there  is  much  less  frictional  resistance  to  the  passage  of 
steam  or  water  than  is  offered  by  the  crooked  channel  of  the 
globe  valve  described  above,  and  the  gate  valve  has  the  further 
advantage  of  weighing  less  and  being  more  compact  than  the 
globe  valve  of  the  same  capacity. 

The  wedge  form  of  valve  and  removable  seat  can  be  seen  in 
the  sectional  view.  By  turning  the  threaded  hand  wheel,  in  Fig. 
12,  the  stem  and  valve  settle  slowly  into  place  and  the  valve  faces 
are  forced  tightly  against  both  valve  seats. 

In  large  gate  valves  the  pressure  may  be  so  great  that  the  valve 
can  be  raised  only  by  applying  great  power  to  the  hand  wheel. 
To  obviate  this  a  smaller  by-pass  valve,  shown  on  the  elevation, 
is  fitted  to  the  chamber,  and,  when  opened,  the  pressure  on  both 
valve  faces  is  soon  equalized  and  the  main  valve  can  be  easily 
opened. 
3 


Fiar.  13. — Hvdrokineter. 


Fig.  14. 


35 


36  MARINE    engines: 

It  may  sometimes  happen  that  it  is  inconvenient  to  have  the 
stem  rise  with  the  valve,  in  which  case  a  modification  is  used: 
the  nut  and  valve  are  in  one,  and  the  threaded  portion  of  the 
stem  is  shrouded  when  the  valve  is  opened.  The  stem  is  pre- 
vented from  rising  by  a  collar  turned  on  it  and  fitting  in  a  recess 
in  the  valve  bonnet.  Models  of  small  sizes  of  these  valves,  in 
section,  are  in  the  model  room. 

CIRCULATING  APPARATUS. 
Art.  13.— (P.  119.  S.  &  O.) 

Because  of  the  enormous  strains  set  up  in  a  cylindrical  boiler 
when  one  part  is  heated  while  the  others  remain  cold,  it  is  neces- 
sary that  the  water  be  made  to  circulate  freely  when  steam  is 
being  raised,  and  thus  be  heated  and  so  heat  the  boiler  shell  uni- 
formly. 

A  method  of  accomplishing  this  result  is  shown  in  Figs.  13  _ 
and  14.  Steam  is  admitted  through  the  hydrokinetcr  from  some 
exterior  source,  and.  as  it  rushes  through  the  nozzles,  draws  the 
surrounding  water  in  through  the  grating  0  surrounding  the  noz- 
zles, discharging  it  forcibly  from  the  nozzle  m.  This  sets  up  local 
circulation,  which  in  turn  sets  all  the  water  in  the  boiler  moving, 
so  heating  it  uniformly. 

They  are  started  some  hours  before  the  fires  are  lighted  in  the 
furnaces  and,  as  all  the  steam  used  in  heating  the  water  enters 
the  boiler,  the  water  level  must  be  left  low  enough  at  the  start  to 
allow  for  the  increase  in  amount  due  to  the  added  steam. 

Another  plan,  generally  used,  is  to  use  one  of  the  auxiliary  feed 
pumps  to  pump  water  out  of  the  bottom  of  the  boiler  and  feed  it 
back  into  the  boiler  through  the  regular  feed  check  valve  and 
distributing  pipes  while  steam  is  being  raised  by  means  of  the 
fires. 

Neither  of  these  methods  of  circulating  the  water  in  the  boiler 
can  be  used  after  the  boiler  is  under  its  full  pressure. 

CENTRIFUGAL  SEPARATOR. 

Art.  14.— (P.  123,  S.  &  O.) 

Figs,  no  and  in  of  the  text-book  show  a  type  of  separator 
in   common  use.     Another  type,  sometimes  used  in  the  U.   S. 


PROBLEMS,  NOTES  AND  SKETCHES. 


37 


navy,  consists  of  a  cylindrical  chamber  with  vanes  so  arranged 
as  to  give  the  entering  steam  a  whirling  motion  and  the  water 
is  thrown  outward  by  centrifugal  force.  A  chamber  underneath 
collects  the  water  and  from  thence  it  is  trapped  to  the  feed-tank. 
A  separator  of  this  kind  is  the  "  De  Rycke,"  shown  in  Fig.  15. 


(Fig.  1.^.) 


STEAAI  TRAPS. 

Art.  15.— (P.  126.  S.  &  O.) 

There  are  various  types  of  steam  traps  in  use  in  the  U.  S.  navy. 
The  trap  shown  on  p.  126  of  the  text-book  represents  one  type, 
being  similar  to  the  Nason  trap. 

Another  type  consists  of  a  chamber  with  an  outlet  valve  oper- 
ated from  the  end  of  a  lever,  with  fulcrum  near  the  valve.  The 
other  end  of  the  lever  carries  a  float  or  bucket.  The  normal 
position  of  the  valve  is  closed,  but  when  the  chamber  fills,  the 
float,  if  used,  rises  and  opens  the  valve.  If  a  bucket  be  used, 
the  bucket  after  rising  to  the  top  of  the  chamber  is  filled  by  the 
water  flowing  into  it  over  the  edge  and,  sinking  to  the  bottom 
of  the  chamber,  opens  the  discharge  valve,  allowing  the  dis- 
charge of  the  water  from  inside  the  bucket:  the  water  in  the 
trap  being  discharged  down  to  the  level  of  the  top  of  the  bucket, 
and  the  water  in  the  bucket  having  been  blown  out,  the  bucket 


38 


MARINE    engines: 


rises,  floating  on  the  water  remaining  in  the  trap,  and  rising 
closes  the  discharge  valve.  A  trap  of  this  description  is  the 
"  Dinkel "  trap,  shown  in  Fig.  i6. 


1  NLET 


(Fig.  16.) 

NOTE. 
CALCULATION  OF  TABLE,  P.  138  S.  &  O. 

Art.  16. — Let  U  =  the  useful  work  done  in  a  given  time  ex- 
pressed in  B.  T.  U. 

Let  0  =  the  heat  expended  in  the  same  time  to  perform  the 
work  U. 


Efificiency  =-^  =  -^ 


^    .      The    efficiency    bein^^    a   maxi- 
^  +  461  y  i> 

mum,  and  T^  and  To  the  limits  of  temperature  between  which  the 

work  is  performed. 

33000 

42.75  B.  T.  U.  expended  per 


Let    U=one  I.  H.  P. 
minute. 


772 


T,  +  461 
Consequently,  ^  =  42.75  X    ^  _  „   ;  T^dindT^hemgXheWm.- 

its,  the  equation  gives  the  minimum  amount  of  heat  which  will 
produce  one  L  H.  P.  when  working  between  these  limits. 


PROBLEMS,  NOTES  AND  SKETCHES.  39 

Let  A''  =  the  number  of  pounds  of  steam  per  I.  H.  P.  per  hour. 

Let  H  =  heat  necessary  to  form  one  pound  of  steam  under  the 
given  conditions  of  temperature  of  feed  and  temperature  of  the 
steam  formed.     Then 

N= Yj —  =  pounds  of  steam  per  L  H.  r.  per  hour. 

ri 

Example. — Case  I;  Condensing  Engine. 

710 

Ti  =  249,  r.  =  100.     Then  0  =  42.75  X =  203.49. 

149 

60  X  20^.49 
iV=^ ^4^ -  =  11.2 

1082  +  .3  X  249  —  (100  —  32) 

Example. — Case  II :  A'on-Condensing  Engine. 
Ti  =  249,  r,  =  212.     Then  0  =  819.945. 

60X819.945 

]V=    ^^jTj' _  CO  ^7 

1082  +  .3  X  249  —  (212  —  32)         -^     "^ 

XOTE. 

CALCULATIOX  OF  AIEAX  EFFECTIVE  PRESSURE 

WHEN  A  GAS  EXPANDS  ACCORDING 

TO  ANY  LAW. 

Art.  17.— (Chap.  NIL,  S.  &  O.) 

Let  />!  :=  the  initial  pressure. 
p^  z=z    "    final  " 

^3  =    "    back  " 

p^=    "    mean  absolute  forward  pressure. 
p^  =    "        "      effective  pressure. 

Pe  =  Pm  —  Pz- 

z\  =  the  initial  volume. 

r.=    "    final 

r   ^  ratio  of  expansion  =—  , 

Pn  =  the  total  area  of  the  card,  Fig.  54  (down  to  the  axis  V), 

A       A 
divided  by  the  leno-th  of  the  card,  or  />„.  =  —  =  —  . 


40 


MARINE    engines: 


Suppose  the  equation  to  the  expansion  curve  of  the  diagram 
be  /?z'"  =  a  constant,  the  area  of  the  portion  bounded  by  the  ex- 
pansion curve  and  the  vertical  ordinates  Hmiting  it  will  be 


(■) 


' pdv  ;   but  /7'"  =  p^v\  —  p^.'l  —  p.^'l  ,  etc., 
from  which  we  get  p  =  -^ . 


Substituting  this  value  for  p  in  the  integral,  the  expression  be- 
comes 

(•"'2  rv-j         /'^■?'\ 

(2)  Expansion  area  =     pdv  =       P\^\\'^\ 


Fiu-.  17. 


To  this  add  the  area  of  the  rectangle  p^i\,  and  the  expression 
for  the  total  area  becomes: 


(3) 


p,v,  +  p,vl 


f^^  di> 


Integrating  equation  (3)  between  the  limits,  remembering  that 

7',  =  rz\ ; 

(4)        Work  area  =  p^v^  +  ^^^^  ~  ^''"'''^  - 


Then  since  /„^  = 


Work  area 


1 


rv. 


(5)  /,.  -  A  X  yjY^—^  ^""^  ^e  =  P.n  -Pi' 

Experiments  have  been  made  with  steam  under  varying  condi- 


PROBLEMS,  NOTES  AND  SKETCHES.  4I 

tions,  and  calculations  from  these  experiments  have  shown  the 
values  of  the  coefficient  )i  to  be  as  given  below: 

(a)  Isothermal  or  Hyperbolic  Expansion,     pv  =  constant. 

The  heat  received  from  the  jacket  or  other  external  source  is 
exactly  equivalent  to  the  external  work  done. 

(b)  Saturated  Steam  Expansion.     pv\i  =  constant. 

The  heat  received  from  the  jacket  or  other  external  source  is 
just  sufficient  to  keep  the  steam  dry  and  saturated.  The  curve  of 
expansion  is  called  the  Saturated  Steam  Curve. 

(c)  Adiabatic  Expansion.     /'7'V-  =  constant. 

The  steam  expands  in  a  non-conducting  cylinder,  doing  work 
at  the  expense  of  the  heat  in  the  steam.  No  heat  is  received  and 
none  is  lost  as  heat.  An  amount  of  heat  is  given  up  exactly 
equivalent  to  the  work  done.  The  curve  of  expansion  is  called 
the  Adiabatic  Curz'c. 

Let  )i  =  I ;  then  the  ecjuation  of  the  expansion  curve  becomes 
that  of  a  rectangular  hyperbola,  and  the  expansion  becomes  hy- 
perbolic and  approaches  that  of  a  perfect  gas. 

Substituting  this  value  for  n,  in  equation  (5),  and  evaluating,  or 
better  still,  substituting  in  equation  (3)  and  integrating;  the  ex- 
pression for  the  mean  absolute  forward  pressure  becomes: 

I  +  hyp.  log.  r 

(6)  A,=AX .  • 


1 


17  /17  —  i6ri*^\ 

(7)  When«  =  ^,A.=Ax(-^-7 ); 

-± 
10  10  — or^ 

(8)  When  n  =  -^,  /„,  =  p^  X  -^   ; 

Note. — The  hyperbolic  logarithm  of  any  number  can  be  found  by  mul- 
tiplying the  common  logarithm  of  the  number  by  2.302585,  or,  as  is  usually 
clone,  by  2.30. 

EXPLANATION  OF  TABLE.  P.  142,  S.  &  O. 

Art.  18. — The  specific  volume,  v,  of  steam  may  be  calculated 
11. 
from  the  formula  pv^^  =  475.     (See  p.  146  of  Sennett  and  Oram.) 


42 


MARINE    engines: 


Assuming  the  first  column  in  the  table,  let 
/>i  =  initial  pressure, 
p.j,  ■=■  final  pressure, 

—  ^  ratio  of  expansion, 
^'i 

ij_  1.1. 

then  since /j^'ji'^  =^.,7/^1 «  , 


ratio  of  expansion  =  - "  = 
''1 


■/i 
-A 


1 0 

— ,  1 7 


10 


Taking  the  case  of  dry  saturated  steam,  the  mean  absolute  pressure 


A„=/iX 


17  —  i6?-i6 


and  the  mean  effective  pressure  p^  —  /,„  —  p^  —  />„,  —  3  . 

The  values  given  in  the  last  column  are  obtained  as  follows  : 
Let  sub  I  represent  the  first  line  of  the  table  and  sub  2  any 

other  line;  then  when 

L  =  length  of  the  stroke  of  the  engine  in  feet, 

P  ^  mean  effective  pressure  per  square  inch  on  the  piston, 

A  ^  area  of  the  piston  in  square  inches, 

iV  =  number  of  strokes  of  the  engine  per  minute, 

the  engine  being  the  same  in  the  two  cases,  the  pressures  and 

revolutions  varying  only: 


(I.  H.  P.), 


^         -^  and  (I.  H.  P.),  =     \ - ;  from  which 


33000 


33000 


(0 


But  PL  = 


2or 


{\.W.Y.\_P,N, 
(I.  H.  P.)2      P^N,; 

and  as   Fis  proportional   to  A^we  may  write 


PL  =  K^T'  where  i^  is  a  constant ;  consequently 


P. 


r.V, 


l^iT 


a: 


or  -^-  = 


which  substituted  in  (i)  gives 

(I.  H.  P.),  _  rP, 


r5 

i^2 


(3) 


(I.  H.  P.)3 


^P,^ 


and  by  substituting  known  values  in  this  equation,  the  results 
found  in  the  last  column  mav  be  calculated. 


PROBLEMS,  NOTES  AND  SKETCHES. 


43 


Problems  on  the  Preceding  Articles. 

33.  What  are  the  least  "  pounds  of  coal  per  I.  H.  P.  per  hour," 
which  would  be  used  by  a  perfect  engine  having  an  initial  pres- 
sure of  steam  of  180  pounds,  where  the  temperature  of  the  steam 
is  373^  and  of  the  feed-water  120'? 

The  coal  used  is  considered  thermally  equal  to  pure  carbon. 

Ans.     .5831  pounds. 

34.  The  least  "  pounds  of  coal  per  I.  H.  P.  per  hour  "  ex- 
pended in  practice  are  1.5  pounds. 

As  compared  with  the  result  of  the  preceding  problem,  what 
actual  efficiency  does  this  show  for  the  modern  engine? 

Ans.     .388. 

35.  How  many  pounds  of  water  must  be  evaporated  per  hour 
under  the  conditions  of  question  33  to  produce  i  I.  H.  P.? 

Alls.     7.646  pounds. 

36.  An  engine,  the  theoretical  card  of  which  is  shown,  makes 
200  revolutions  per  minute. 


Fig-.  18. 

Area  of  piston  =  300  square  inches. 
Stroke  =  40  inches. 

Cut-off  is  at  4  inches  from  beginning  of  stroke. 
Temperature  of  feed  =    110°. 

Initial  pressure  of  the  steam  ^  60  pounds  per  square  inch. 
Initial  temperature  of  the  steam  =  293°. 

Required  to  find  the  I.  H.  P.  developed  by  the  engine,  and  the 
number  of  B.  T.  U.  expended. 

Ans.     215.7  I-  H.  P.,  42500  B.  T.  U.  expended  per  minute. 


44  MARINE  engines: 

2^^.     Find  the  efificiency  of  the  engine  of  question  36. 

Ans.     2\.6  per  cent. 

38.  With  the  steam  used  in  question  36,  find  the  maximum 
efficiency  theoretically  attainable  if  the  steam  be  used  in  an  en- 
j^ine.  Alls.     22.2  per  cent. 

39.  If  this  maximum  efficiency  be  considered  perfection,  as  is 
the  case  for  steam  between  these  temperatures,  what  is  the  effi- 
ciency of  the  engine?  Aiis.     97  per  cent. 

40.  Suppose  an  engine  to  work  between  the  limits  of  pressure 
of  100  pounds  and  18  pounds  per  square  inch,  temperatures  of 
the  steam  327.5°  and  222.4' ;  ^"<J  then  the  same  engine  to  work 
between  the  limits  of  100  pounds  and  2  pounds  per  square  inch, 
temperatures  of  the  steam  327.5°  and  126.2°;  compare  the  effi- 
ciency of  the  steam  in  the  two  methods  of  working. 

Ans.     As  105. 1  is  to  201.3. 

41.  Suppose  the  curve  of  expansion  in  each  of  the  above  cases 
of  Problem  40,  be  pz'  =:  a  constant. 

Compare  the  am.ount  of  work  done  by  the  same  amount  of 
steam  in  the  two  methods  of  working. 

Ans.     Work  done  in  first  case  is  to  work  done  in 
second  case  as  .553  is  to  i. 

42.  In  the  table,  given  on  p.  138  of  the  text,  calculate  the  last 
line,  taking  the  temperatures  from  the  tables. 

43.  A  cylinder  full  of  steam  of  4  pounds  pressure  per  square 
inch  and  153°  temperature  is  discharged  to  a  condenser  at  the 
end  of  each  stroke  of  the  engine. 

The  dimensions  of  the  cylinder  =r  3'  x  3'. 

It  is  desired  to  make  the  temperature  of  the  condensed,  or  feed- 
water  110°.  the  temperature  of  the  injection,  or  sea-water  being 
80°. 

If  a  jet  condenser  be  used,  how  many  pounds  of  sea-water  will 
be  required  per  stroke  of  the  engine  as  injection  water? 

A)is.     8.25  pounds. 

44.  Suppose  that  a  surface  condenser  were  used  with  the  en- 
gine of  question  43,  and  that  the  temperature  of  the  discharge 
water  were  100°,  how  many  pounds  of  injection  water  would 
then  be  required  per  stroke?  Ans.     12.38  pounds. 


PROBLEMS,  NOTES  AND  SKETCHES.  45 

45.  One  pound  of  steam  of  lOO  pounds  pressure  per  square 
inch  contains  20  per  cent,  moisture;  what  vohmie  will  it  occupy? 

Alls.     3.5256  cubic  feet. 

46.  Calculate  the  second  line  of  the  table  given  on  p.  142  of 
the  text. 

47.  Calculate  the  last  line  of  the  table  given  on  p.  142  of  the 
text. 

48.  With  an  initial  pressure  of  100  pounds,  a  back  pressure 
of  3  pounds,  and  a  ratio  of  expansion  of  12,  calculate  the  mean 
effective  pressure  when  dry  steam  expands  in  a  jacketed  cylinder 
and  the  jacket  furnishes  as  much  heat  as  is  used  up  in  work;  in 
a  non-conducting  cylinder;  in  a  jacketed  cylinder,  the  jacket  fur- 
nishing just  enough  heat  to  keep  the  steam  dry  throughout  the 
stroke. 

49.  With  the  same  conditions  as  to  expansion,  find  the  mean 
effective  pressure,  having  given  an  initial  pressure  =:  50  pounds, 
back  pressure  =  2  pounds,  and  a  ratio  of  expansion  :=  4. 

50.  With  the  same  conditions  as  to  expansion,  find  the  mean 
effective  pressure,  having  given  an  initial  pressure  =  60  pounds, 
back  pressure  r=  5  pounds,  and  a  ratio  of  expansion  =  10.  Also 
find  the  final  pressure. 

In  the  follozving  problems  on  change  in  I.  H.  P.  for  given  changes 
in  the  performance  of  the  engine,  it  is  to  he  understood  that  the  num- 
ber of  revolutions  cannot  change  unless  the  mean  effective  prcssnre 
changes,  the  resistance  remaining  constant. 

51.  An  engine  making  50  revolutions  per  minute  develops 
200  I.  H.  P.  Suppose  that  the  revolutions  are  increased  to  60 
per  minute;  what  will  then  be  the  I.  H.  P.?  Ans.     345.6. 

52.  An  engine  is  making  100  revolutions  per  minute,  and  the 
mean  effective  pressure,  as  shown  by  the  card,  is  15  pounds  per 
square  inch.  If  the  mean  effective  pressure  on  the  piston  be 
increased  to  20  pounds  per  square  inch,  what  number  of  revolu- 
tions per  minute  may  the  engine  be  expected  to  make? 

Ans.     115.47- 

53.  If,  in  question  (52),  the  I.  H.  P.  were,  in  the  first  instance, 
250,  what  I.  H.  P.  would  be  developed  under  the  new  conditions? 

Ans.     384.9. 

54.  If  the  revolutions  of  an  engine  be  doubled,  what  is  the 
increase  in  the  I.  H.  P.?  Ans.     Eight  fold. 


46 


MARINE    engines: 


55.  If  the  number  of  revolutions  made  by  an  engine  be  in- 
creased by  10  per  cent.,  what  is  the  percentage  of  increase  in  the 
I.  H.  P.?  A71S.     33  per  cent. 

56.  If  the  mean  effective  pressure  on  the  piston  of  an  engine 
])e  increased  10  per  cent.,  what  will  be  the  percentage  of  increase 
in  the  I.  H.  P.,  and  in  the  number  of  revolutions  per  minute? 

Ans.     15  per  cent,  in  I.  H.  P.,  and  5  per  cent,  in  revolutions. 

57.  The  I.  H.  P.  varies  as  the  number  of  revolutions  of  the 
engine  raised  to  what  power?  Ans.     To  the  third  power. 


NOTES  ON  THE  ZEUNER  VALVE  DIAGRAM. 

Art.  19.— (P.  184,  S.  &  O.) 

In  the  notes  which  follow  it  is  assumed  that  the  length  of 
eccentric  rod  is  infinite.  This,  as  a  matter  of  fact,  is  not  true, 
but  the  ratio  of  length  of  eccentric-rod  to  throw  of  eccentric  is 
so  large  that  the  error  involved  in  the  diagram  is  insignificant. 

Suppose  Fig.  19  to  be 
drawn  to  a  scale  such  that 
CF3  represents  the  full 
travel  of  the  valve.  P  rep- 
resents the  position  of  the 
eccentric  when  the  crank  is 
on  the  dead  centre,  at  C. 
The  angle  FOR  then  repre- 
sents the  angle  of  advance, 
and  the  distance  OA  repre- 
sents the  distance  the  valve 
has  moved  from  its  mid-po- 
sition, at  the  beginning  of 
the  stroke. 

If  the  crank  moves  to  positions  C^,  C^,  E^,  the  eccentric  moves 
through  equal  angles  to  corresponding  positions  P^,  P^,  Pz-  As 
drawn  the  figure  shows  P^  the  position  of  the  eccentric  when 
the  valve  has  reached  its  full  travel  to  the  right.  It  is  evident 
that  the  crank  at  the  same  time  reaches  a  position  £3,  such  that 
the  angle  ROE^  ^=.  the  angle  of  advance  ROP .  For  the  differ- 
ent positions  C,  C^,  Co.  £3,  of  the  crank,  the  travel  of  the  valve 
from  its  mid-position  is  to  OA,  OA^,  OA^,  and  OP3,  respectively. 


Fiff.  19. 


PROBLEMS,  NOTES  AND  SKETCHES. 


47 


Now  sweep  these  positions  around  to  E,  E-^,  E^,  and  £3,  to  the 
Hnes  joining  the  centre  with  the  corresponding  positions  of  the 
crank.  Join  £3  with  any  one  of  the  other  points,  say  with  £^. 
Then,  in  the  triangles  P-^^OA^  and  E^OE^,  we  have  the  hnes  P^O 
and  OA-^  and  the  angle  P^OA^  =  respectively  to  the  lines  £30 
and  0£i  and  the  angle  E^OE^,  by  construction.  Therefore,  the 
triangles  are  equal  and  the  angle  EM^O  is  equal  to  the  angle 
P-^Aj^O,  which  is  a  right  angle.  The  point  E^  is  therefore  on  a 
circle  drawn  on  the  line  £30  as  a  diameter. 

This  proves  that  if  we  take  the  crank  as  starting  from  the 
centre  C,  and  turning  to  the  right,  and  lay  off  an  angle  ROE^  on 
the  side  next  to  the  crank  :=  to  the  angle  of  advance,  and  on  OE^ 
as  a  diameter,  construct  a  circle:- — a  line  drawn  from  the  centre 
of  the  large  circle  to  any  position  of  the  crank,  such  as  M,  will 
intercept  a  distance  ON ,  =  to  the  travel  of  the  valve. 

Lap. — When  the  valve  is  in  its  mid-position,  the  amount  that 
it  overlaps  the  edge  of  the  port  is  called  the  lap.  The  amount  that 
it  overlaps  on  the  steam  side  is  called  the  steam  lap  and  the 
amount  that  it  overlaps  on  the  exhaust  side  is  called  the  exhaust 
lap.  (The  laps  are  sometimes  spoken  of  as  the  inside  and  out- 
side lap.)  Before  the  steam  port  can  open,  the  valve  must  travel 
a  distance  r=  to  the  lap.  After  it  has  opened,  the  amount  of  its 
opening  will  always  =  the  travel  —  the  lap.  If,  therefore,  on 
the  diagram  (Fig.  20),  a  circle  be  drawn  with  radius  OM  =  the 
lap,  the  port  opening  for  any  position  of  the  crank  5"  will  be  the 
length  of  the  intercept  VIV,  between  the  valve  circle  and  the  lap 
circle.  At  the  point  K  this 
gives  the  opening  of  the  port 
=  0.  K  therefore,  is  the 
point  where  the  valve  begins 
to  open,  and  is  called  the  point 
of  admission.  At  P  the  open- 
ing is  again  =  0,  and  this  is 
the  point  of  cut-off. 

Lead. — The  amount  that 
the  valve  is  opened  to  steam 
at  the  beginning  of  the  stroke 
of  the  piston  is  called  the 
steam  lead.  In  Fig.  20  it  is 
the    length    of    the    intercept 


Fig.  20. 


48  MARINE  engines: 

NQ  on  the  line  of  dead  centres.  Similarly,  the  amount  that  the 
valve  is  opened  to  exhaust  at  the  end  of  the  stroke  of  piston,  is 
called  the  exhaust  lead. 

Certain  geometrical  properties  of  the  diagram  will  now  be  ex- 
plained.    By  their  aid,  several  of  the  problems  are  solved. 

1.  A  perpendicular  let  fall  from  the  point  corresponding  to 
the  angle  of  advance  (C3,  Fig.  20),  cuts  the  line  of  dead  centres 
at  a  distance  from  the  centre  =:  Lap  +  Lead. 

This  proposition  is  evident  on  examination  of  Fig.  20. 

2.  A  line  joining  the  points  of  admission  and  cut-ofT  is  tan- 
gent to  the  steam  lap  circle. 

Proof. — In  Fig.  20  the  triangles  C.,OL  and  POM  have  the 
sides  PO  and  MO  =  respectively,  to  C^O  and  LO,  and  the  angle 
C^OP  is  common.  The  triangles  are  therefore  equal  and  angle 
PMO  =  angle  C^LO,  which  is  a  right  angle.  PM  is  therefore 
tangent  to  the  lap  circle. 

3.  If  with  centre  at  the  dead  point  C,  and  radius  ^  the  Lead, 
a  circle  be  drawn,  it  will  be  tangent  to  the  line  KP,  joining  the 
points  of  admission  and  cut-olif. 

Proof. — Through  C  draw  CX  parallel  to  KP,  and  therefore 
perpendicular  to  C3O.  The  lines  CO  and  C^O  are  equal;  angles 
OCX  and  OC^N  are  equal;  and  angle  COC.^  is  common  to  both 
triangles.  Therefore  triangles  COX  and  C^ON  are  equal,  XO  = 
NO,  and  XM  =  NO.  But  NQ  =  the  Lead.  Therefore  CR  = 
XM  =  the  Lead. 

4.  If  OF  be  drawn  perpendicular  to  OC^,  a  perpendicular 
from  F  on  the  admission  line,  wuU  be  equal  to  the  steam  lap. 

Proof. — It  will  be  readily  seen  that  triangles  FOY  and  OKM 
are  equal;  therefore  FF  =  OM. 

This  property  is  made  use  of  in  constructing  the  exhaust  part 
of  the  diagram,  whenever  the  lap  circle  is  so  small  that  it  does  not 
give  a  sharp  intersection  with  the  valve  circle. 

The  foregoing  has  referred  to  the  steam  side  of  the  valve 
particularly.  The  exhaust  side  is  considered  in  the  same  way; 
but,  with  the  piston  making  the  return  stroke,  from  P^  to  C. 
The  diagram  then  comes  in  the  lower  half  of  the  figure.  The 
angle  of  advance  and  the  travel  of  the  valve  are  the  same,  but 
the  lap  is  the  inside  or  exhaust  lap.     The  exhaust  lead  and  the 


PROBLEMS,  XOTES  AND  SKETCHES. 


49 


points  of  release  and  compression  correspond  respectively  to  the 
steam  lead  and  the  points  of  admission  and  cut-off,  and  are  ob- 
tained in  the  same  way. 

Fig.  21  shows  a  complete 
diagram,  which  gives  the 
following  information : 

1.  Admission  at  K,  given 
by  angle  KOC. 

2.  Ciit-of¥  at  P,  given  by 
angle  POC. 

3.  Steam  Lap  ^  OQ. 

4.  Steam  Lead  =  NO. 

5.  Maximum  opening  of 
steam  port  ^  CJ\I. 

6.  Angle  of  advance  ^ 
C,OR. 

7.  Travel  of  the  valve  := 
CP,. 

8..  Release  at  Fo,  given  by  angle  P.-.OP^. 

9.  Compression  at  A',,  given  by  angle  K.^OC. 

10.  Exhaust  Lap  ==  OQ^. 

11.  Exhaust  Lead  =  A^iOi- 

12.  Maximum  opening  of  exhaust  port  :=  C ^M.^^. 

Points  I,  2,  9  and  10  must  be  given,  and  are  measured  on  the 
valve  diagram,  by  the  angular  distances  of  the  crank  from  the  be- 
ginning or  end  of  the  stroke,  corresponding  to  these  points.  Fre- 
quently these  points  are  given  in  data  for  problems,  as  taking 
place  at  a  certain  part  of  the  stroke.  In  order  to  find  the  angu- 
lar position  corresponding  to  such  data,  the  circle  representing 
the  travel  of  the  valve  must  be  made  to  represent,  temporarily, 
the  crank  circle  on  a  new  scale;  or,  a  second  circle  of  reference, 
representing  the  crank  circle,  may  be  drawn.  A  good  plan  is 
to  draw  it  concentric  with  the  valve  diagram. 

Suppose  the  cut-ofif  to  be  given  as  at  ^'s  of  the  stroke.  Draw 
the  crank  circle  CFF3  (Fig.  22),  CP^  representing  the  stroke  of 
the  engine.  Lay  ofif  CA  =  ^  of  CP^,  and  with  a  radius  = 
length  of  connecting  rod,  on  the  scale  of  the  diagram,  sweep  A 
up  to  P.  Angle  COP  is  the  angular  distance  from  the  beginning 
of  the  stroke  at  which  cut-ofif  takes  place.  This  angle  can  then 
be  transferred  to  the  valve  diagram. 
4 


50 


MARINE    engines: 


Points  I — 7  belong  to  the  steam  side  of  the  diagram  and  points 
6 — 12  to  the  exhaust  side,  points  6  and  7  being  common  to  both 
sides.  To  construct  the  complete  diagram  it  is  necessary  to 
have  four  of  these  points.  Three  are  sufficient  to  construct  the 
steam  or  exhaust  side  alone;  but  one  or  two  of  the  points  must 
belong  to  a  different  side  from  the  others,  to  construct  the  com- 
plete diagram.  One  of  the  points  must  be  one  of  the  linear 
measurements  on  the  diagram,  /'.  c.  points  3,  4,  5,  7,  10,  11,  or 
12.  This  is  seen  from  the  fact  that  with  only  angles  given,  the 
linear  dimensions  of  the  valve  might  be  made  anything  we  please, 
except  that  they  must  bear  a  certain  ratio  to  one  another. 

The  TvidtJi  of  port  in  the  face  of  cylinder  is  often  given  as  a 
part  of  the  data.  This  may  be  taken  as  the  maximum  opening 
of  the  exhaust  port,  since  the  opening  to  exhaust  will  be  greater 
than  the  opening  to  steam,  and  the  port  is  only  made  sufficiently 
wide  to  allow  full  opening. 

Problem  L — Given  travel 
of  valve  and  points  of  admis- 
sion, cut-off  and  release. 

Referring  to  Fig.  21;  let 
CP3  =  the  given  travel.  On 
CP3  as  a  diameter,  construct 
the  circle  CPC^.  K,  P  and. 
Pr,  are  the  given  points, 
found  with  the  data  given. 
Through  K  and  P  draw  KP, 
through  0  draw  C^C^  per- 
pendicular to  KP,  and 
through  Po  draw  PoK-^  par- 
allel to  KP.  M  and  M^  are  thus  given  and,  by  drawing  the 
valve  circles  on  OC3  and  OC^  and  the  lap  circles  through  M  and 
Mj,  the  leads  are  given. 


Fijr,  22. 


Problem  II. — Given  trazrl  of  valve, 
and  any  point  in  the  exhaust  diagram. 

Construct  the  circle  CPC^  as  before, 
lead,  and  erect  the  perpendicular  NC^. 


steam   lap,   steam   lead, 

Lay  ofif  O.V=lap-|- 
CfiR  is  the  angle  of 


advance.     The  remainder  of  the  construction  will  be  plain. 


Problem  III. — Given  travel  of 
exhaust  lap. 


'alve,  cut-oft',  steam  lead,  and 


PROBLEMS,  NOTES  AND  SKETCHES. 


51 


Construct  the  circle  CPC^  as  before  and  mark  the  point  P  with 
the  data  given.  With  centre  C  and  radius  =  the  lead,  draw  a 
circle.  Through  P  draw  a  line  passing  tangent  to  this  circle  be- 
low C.  This  cuts  the  large  circle  in  K,  the  point  of  admission. 
Draw  a  diameter  to  the  large  circle  perpendicular  to  KP.  This 
gives  the  angle  of  advance  and  the  remainder  of  the  construction 
will  be  plain. 

Problem  IV. — Given  steam  lap,  steam  lead,  and  the  point  of 
cut-off. 

In  Fig.  21,  let  COP  = 
the  angle  corresponding  to 
the  point  of  cut-off.  Draw 
the  lap  circle  QL,  and  lay 
off  QN  =  the  given  lead. 
Construct  a  circle  passing 
through  the  three  points  A^, 
0,  and  L.  This  will  be  the 
valve  circle  and  its  diame- 
ter =  the  half  travel  of  the 
valve. 

Problem  V. — Given  cut- 
off, release,  compression, 
and  width  of  port. 

The  zi'idth  of  port  is  taken  as  equivalent  to  the  maximum 
opening  of  exhaust  port. 

Draw  a  circle  of  indefinite  radius  (Fig.  23)  and  mark  on  it  the 
points  of  cut-off,  release,  and  compression.  Join  the  points  of 
release  and  compression  by  the  line  AB,  and  through  0  draw  a 
diameter  perpendicular  to  AB.     Then: 


Travel  of  valve 


WY 


given  width  of  port      XY 


From  this  the  travel  of  the  valve  is  obtained  and  the  diagram 
may  be  constructed.  If  the  lead  is  given  instead  of  the  width  of 
port:  through  P  draw  a  line  parallel  to  AB  and  from  C  let  fall  a 
perpendicular  CE  upon  it.     Then 

Travel  of  valve       WY 
given  lead  CE 


52  MARINE    engines: 

Problems. 

Note. — Bring  paper,  dividers  and  scale  to  this  recitation. 

Note. — In  the  following  problems  will  be  found  many  badl_\  arranged 
valves;  some  of  them  would  probably  not  permit  the  engine  to  work.  In 
such  cases  the  student  will  be  required  to  show  what  alterations  should  be 
made  to  secure  efficiency. 

58.  Tlie  travel  of  a  valve  is  6".  The  cut-off  occurs  when  the 
crank  has  completed  105°  of  its  path.  Admission  of  steam  be- 
gins when  the  crank  is  within  7.5°  of  the  beginning  of  its  stroke. 
Exhaust  closes  when  crank  is  60°  from  the  end  of  its  stroke. 

Construct  the  Zcuner  valve  diagram  and  find : 
Steam  lap ;  steam  lead ;  exhaust  lap ;  exhaust  lead ;  angle  of  ad- 
vance. 

59.  Travel  of  the  valve  =r  5".  Steam  lap  =  1".  Exhatist 
lap  =  54".     Steam  lead  =  >4". 

Find  and  measure  the  angle  of  advance. 

If  the  stroke  of  the  engine  =  4',  and  the  connecting  rod  be 
considered  as  infinite,  how  far  is  the  piston  from  the  end  of  its 
stroke  when  cut-oflf  occurs? 

60.  What  should  be  the  steam  lap  of  the  valve  in  the  preced- 
ing question,  so  that  the  steam  would  be  cut  ofT  at  half  stroke? 

61.  What  angle  of  advance  should  be  given  the  valve  of  the 
engine  of  question  59,  so  that  it  would  cut  off  at  half  stroke? 

How  would  this  change  affect  the  other  functions  of  the  valve? 

62.  Stroke  of  engine  =  3'.  Length  of  the  connecting  rod  := 
5'.  The  valve  has  an  exhaust  lap  of  yl" ,  and  a  steam  lap  of  i". 
The  maximum  port  opening  for  exhaust  is  2.y^".  Compression 
begins  when  the  piston  is  12"  from  the  end  of  its  stroke. 

Find  the  travel  of  the  valve,  and  the  angle  of  advance. 

63.  The  valve,  a  sketch  of  which  is  shown,  is  to  have  a  travel 

^^^^^^^^  just    suflficient    to    open 

the  port  wide  for  ex- 
haust when  the  exhaust 
is  a  maximum. 

With  an  infinite  con- 
necting rod,  it  is  to  cut 
ofif  at  .75  of  the  stroke 
Fiff-  34.  of  the  ensfine. 


PROBLEMS,  NOTES  AND  SKETCHES.  53 

The  exhaust  is  to  begin  to  open  when  the  piston  is  at  y^,  of  its 
stroke  from  the  end,  and  the  admission  to  occur  jV  of  the  stroke 
from  the  end  of  the  stroke  of  the  piston. 

Find  the  steam  and  exhaust  laps,  the  travel  of  the  valve,  the 
angle  of  advance  of  the  eccentric,  and  the  position  of  the  piston 
at  exhaust  closure. 

64.  In  a  given  engine  the  cut-ofif  is  to  occur  when  the  crank 
is  within  45°  of  the  end  of  its  stroke,  the  release  within  15°  of 
the  end  of  the  stroke,  and  the  admission  to  begin  7.5°  from  the 
beginning  of  the  stroke. 

Maximum  exhaust  port  opening  2.5  inches. 
Find  the  travel  of  the  valve,  steam  and  exhaust  laps,  crank 
angle  when  compression  begins,  and  the  steam  and  exhaust  leads. 

65.  Stroke  of  an  engine  =  3'.     Length  of  its  connecting  rod 

=  5'- 

When  cut-off  occurs,  the  piston  is  2'  from  the  beginning  of  the 

stroke.     When  release  occurs,  the  piston  is  5"  from  the  end  of 

the  stroke,  and  when  compression  begins,  at  10"  from  the  end  of 

the  stroke.     The  maximum  opening  of  the  port  for  steam  is  i", 

and  for  exhaust  is  2". 

Construct  the  diagram  and  measure  the  angular  advance. 

Make  a  section  of  the  valve  and  its  seat  to  a  scale  of  3"  =  i', 
and  show  the  dimensions  of  all  the  parts. 

66.  Steam  lap  =  2" ;  exhaust  lap  ==  i";  angle  of  advance  = 
30° ;  cut-ofif  at  .75  of  the  stroke.  Having  an  infinite  connecting 
rod,  construct  the  diagram. 

This  diagram  being  that  of  an  engine  with  link  in  full  gear, 
show  how  it  would  be  affected  by  open  rods;  by  crossed  rods;  and 
by  raising  the  link  in  each  case  one-half. 

If,  instead  of  a  li)ik  motion,  a  radial  gear  be  used  and  the  ciit-ofF 
be  shortened  by  raising  the  reversing  lever,  show  how  the  dia- 
gram would  be  affected. 

67.  Travel  of  the  valve  =  6";  cut-off  at  half  stroke;  angle  of 
advance  of  the  eccentric  =  30° ;  exhaust  lap  =  ^2".  Construct 
the  diagram. 

(0)  Construct  the  theoretical  indicator  card,  with  an  initial 
pressure  of  100  pounds  to  the  square  inch,  the  scale  of  the  indi- 
cator being  25  pounds  =1".  and  the  curve  of  expansion  having 
the  form  pv  =  a  constant. 


54  MARINE  engines: 

(b)  If  the  angular  advance  be  diminished,  show  how  the  dia- 
gram and  the  indicator  card  will  be  afifected. 

(c)  What  alteration  in  the  data  might  be  made  so  that  an  ear- 
lier exhaust  closure  would  follow? 

68.  Steam  lead  ^  i/^";  steam  lap  =1";  exhaust  lead  ^  ^"; 
travel  of  the-  valve  =  3". 

Construct  the  diagram  and  make  a  sketch  of  the  valve  and  its 
seat  to  a  scale  of  4"  =  1'.  Mark  all  the  dimensions  on  the 
sketch. 

69.  If  the  stroke  of  the  piston  of  the  above  engine  be  3',  sketch 
the  theoretical  indicator  card.  The  initial  pressure  is  80  pounds 
per  square  inch,  and  the  scale  of  the  indicator  is  30  pounds  =  1". 
The  curve  of  expansion  is  of  the  form  given  by  the  equation 
pv  =:  a  constant. 

Art.  2c^-(P.  261,  S.  &  O.) 

In  ships  having  double  bottoms,  it  is  necessary  to  fit  a  special 
nozzle  for  all  valves  which  are  intended  to  admit  sea  water  for 
various  uses  on  board. 

Fig.  25  shows  one  method  of  doing  this,  the  nozzle  being 
shown  part  in  elevation  and  part  in  section. 

In  the  outer  bottom  b  a  hole  is  cut,  around  which,  to  compen- 
sate for  the  loss  of  strength  due  to  cutting  away  the  metal,  is 
riveted  a  cast  steel  ring  c  in  which  are  fitted  a  number  of  stud 
bolts.  A  sine  ring  k  is  fitted  snugly  in  the  hole  thus  made,  and 
is  secured  to  the  ring  c  with  countersunk  screws,  as  shown. 

A  hole  having  been  cut  in  the  inner  bottom  a,  large  enough  to 
permit  the  passage  of  the  bottom  flange  of  the  nozzle  d,  this 
nozzle  is  then  passed  through  and  secured  to  the  stud  bolts  in  c. 
The  nozzle  d  has  an  inner  fllange,  in  which  are  screwed  several 
stud  bolts  h,  whose  middle  unthreaded  portions  are  square. 
Over  these  studs  is  fitted  the  grating  g,  having  square  holes  to 
correspond  to  the  square  studs,  and  nuts  are  screwed  on  the  ends 
of  the  studs  and  secured  with  split-pins  run  through  holes  in  the 
studs. 

A  plate  f,  having  a  stufifing-box  cast  with  it,  is  then  passed 
over  the  end  of  the  nozzle,  and  is  bolted  to  the  inner  bottom  a. 
Stud  bolts  are  screwed  in  f  around  the  stuffing-box,  and  serve  to 
hold  in  place  the  gland,  which  is  passed  over  the  end  of  the  nozzle 


PROBLEMS,  NOTES  AND  SKETCHES. 


55 


and  screwed  down  after  the  stuffing-box  has  been  filled  with 
several  turns  of  square  iiax  packing.  Last  of  all  the  flange  e  is 
screwed  on  the  end  of  the  nozzle  which  has  been  threaded  for 
this  purpose. 


Fig.  25. 


The  zinc  ring  k  protects  the  bottom  of  the  ship  from  pitting  by 
being  eaten  away  gradually  during  the  electrolytic  action  which 
is  set  up  by  running 'salt  water  through  the  steel  skin  of  the  ship 
and  the  composition  nozzle. 


56  MARINE    engines: 

The  grating  g  prevents  the  entrance  of  large  pieces  of  foreign 
matter,  and  can  be  readily  removed,  if  necessary,  when  in  dock. 
The  area  of  the  holes  in  this  is  about  1.75  times  the  area  of  the 
valve  attached  to  the  nozzle,  and  this  excess  area  and  the  large 
conical  mouth  of  the  nozzle  permit  the  inner  pipe  to  receive  a 
full  supply  of  water. 

Should  the  ship  ground  and  the  outer  bottom  be  pierced,  the 
water  cannot  pass  the  inner  bottom,  and  if  the  outer  bottom  be 
sprung,  the  nozzle,  being  free  to  move,  will  not  be  broken  away, 
nor  will  the  inner  bottom  be  afifected. 

The  upper  flange  c  must  be  screwed  on,  as  otherwise  the  stuf- 
fing-box and  gland  could  not  be  passed  over  the  nozzle. 

Problems. 
(To  follow  p.  267,  S.  &  O.) 

70.  The  temperature  of  the  steam  =  300°.  Saturation  to  be 
maintained  =  o\.  Density  of  the  feed  water  =  ttV,  and  tempera- 
ture of  the  feed  =  60°.  What  percentage  of  the  heat  is  lost  by 
blowing  off?  Alls.     9.5  per  cent. 

71.  The  temperature  of  the  steam  =  300^,  temperature  of  the 
feed  =  75°.  and  the  density  of  the  feed  =  75V.  What  percentage 
in  gain  of  heat  will  there  be  if  the  density  in  the  boiler  be  carried 
at  o^V  instead  of -tV~  ?  Arts.  16.2  per  cent. 

^2.  The  temperature  of  the  steam  =r  250^.  Temperature  of 
the  feed  =  60°.  Density  of  feed  =  3^-  Density  to  be  main- 
tained =  4n.  Find  the  percentage  of  loss  of  heat  due  to  blow- 
ing off  in  order  to  keep  the  saturation  constant. 

Ans.     3.25  per  cent. 

y^.  The  temperature  of  the  steam  is  325°,  and  of  the  feed  32°. 
The  density  to  be  maintained  is  /j,  and  the  density  of  the  feed 

Find  the  percentage  of  loss  due  to  blowing  ofi  the  boiler  to 
maintain  a  constant  saturation.  Ans.     2>A^  P^r  cent. 

74.  The  density  to  be  maintained  is-V#--  The  temperature  of 
the  feed  is  100°  and  its  density  is  ^V.  The  temperature  of  the 
steam  is  275°. 

Find  the  loss  due  to  blowing  off  the  boiler  to  maintain  a  con- 
stant saturation.  Ans.     24  per  cent. 


PROBLEMS,  NOTES  AND  SKETCHES.  57 

75.  Density  to  be  maintained  is  -^%.  The  other  data  are  the 
same  as  in  the  preceding  problem. 

Find  the  amount  of  feed  water  necessary  that  there  mav  con- 
stantly be  delivered  to  the  engine  an  amount  of  steam  sufBcient 
to  produce  a  mean  piston  speed  of  900  feet  per  minute. 

The  cylinder  is  3'  in  diameter,  has  a  stroke  of  3'.  and  cuts  off 
at  .75  of  its  stroke.        -  '•■^  "^ 

Note. — The  commercial  horse  power  of  a  boiler  is  measured  bj'  the 
evaporative  efficiency  of  the  boiler. 

If  a  boiler  evaporate  30  pounds  of  water  per  hour,  from  feed  water 
having  a  temperature  of  100°  to  steam  of  70  pounds  pressure  per  square 
inch,  it  is  said  to  develop  one  commercial  horse  power. 

76.  How  many  pounds  of  water  must  be  evaporated,  from  and 
at  212°.  to  be  equivalent  to  one  commercial  horse  power? 

Arts.     34.488  pounds. 
yy.     How  many  heat  luiits  are  there  in  one  commercial  horse 
power?  Ans.     33,189. 

78.  \Miat  would  be  the  commercial  horse  power  of  the  boiler 
required  to  supply  steam  to  the  engine  of  Problem  75? 

Ans.     1060.7  commercial  horse  power. 

79.  A  steam  cutter  engine  has  a  cylinder  6"  in  diameter,  and 
the  stroke  of  the  engine  is  6".  The  cut-off  is  at  .75  of  the 
stroke;  the  initial  pressure  of  the  steam  is  80  pounds  per  square 
inch;  the  temperature  of  the  feed  is  76°,  and  the  engine  makes 
300  revolutions  per  minute.  What  must  be  the  commercial  horse 
power  of  the  boiler  necessary  to  supply  this  engine  with  steam? 

Alls.     19.425  commercial  horse  power. 

NOTES  ON  THE  STEAM  TURBIXE. 
Art.  21.— (Chap.  XXH,  S.  &  O.) 

The  following  notes  are  intended  merely  to  give  a  general 
idea  of  the  steam  turbine,  with  some  data  on  its  economical  per- 
formance. 

At  present  the  two  leading  turbines  are  the  Parsons  and  the 
De  Laval. 

The  first  large  installation  of  steam  turbines  was  in  1891,  when 
the  electric  light  station  at  Cambridge,  England,  was  fitted  with 
alternating  current  machines,  driven  by  Parsons'  Improved  Com- 


58  MARINE  engines: 

pound  Condensing  Steam  Turbines,  directly  connected.  The  in- 
stallation was  thoroughly  tested  by  Prof.  Ewing,  F.  R.  S.,  Pro- 
fessor of  Engineering  at  the  University  of  Cambridge.  These 
tests  showed  a  steam  consumption  of  74.5  pounds  per  kilowatt- 
hour,  wath  very  light  load;  32.2  pounds,  with  half  load;  and  28.4 
pounds,  with  full  load;  using  steam  very  slightly  superheated. 
The  turbine  cannot  be  indicated  as  the  reciprocating  engine  can, 
and  the  measure  of  work  must  be  the  actual  work  performed. 
By  constructing  curves  of  work,  somewhat  similar  to  the  curves 
of  indicated  thrust,  constructed  by  Dr.  Froude  (Sennett  &  Oram, 
p.  302),  Prof.  Ewing  estimated  the  idle  work  to  be  about  25 
per  cent,  and  the  efficiency  about  75  per  cent.  On  this  basis, 
the  steam  consumed,  per  I.  H.  P.,  was  about  15.5  pounds  at  full 
load,  and  about  17  pounds  at  half  load.  These  results  showed 
the  marked  superiority  of  the  turbine  at  light  loads,  and  its  effi- 
ciency compares  well  with  that  of  the  best  reciprocating  engine 
at  full  loads. 

Further  tests  were  made  to  show  the  effect,  on  efficiency,  of 
using  steam  highly  superheated.  It  was  shown  that  by  super- 
heating the  steam  sufficiently  to  cause  it  to  be  dry  at  the  end  of 
the  expansion,  a  marked  saving  was  effected;  and  further  super- 
heating did  but  little  good. 

This  tvirbine  is  described  by  Prof.  Ewing  as  follows: 
The  turbine  case  contains  a  series  of  seven  revolving  discs, 
from  the  surface  of  which  the  turbine  blades  project.  They  are 
arranged  on  each  disc  in  a  series  of  concentric  rings.  The  fixed 
guide  blades  stand  in  spaces  between  these  rings,  being  carried 
by  annular  discs  which  are  fixed  to  the  case.  Thus  each  revolv- 
ing disc,  with  its  neighboring  fixed  disc,  forms  a  series  of  outward 
flow  turbines,  the  steam  entering  the  series  inside  the  smallest 
ring  of  blades  and  escaping  at  the  circumference  into  a  channel, 
which  conducts  it  between  the  backs  of  the  revolving  disc  and 
of  the  next  fixed  disc  to  the  inside  of  the  next  series  of  rings. 
The  heights  and  apertures  of  the  turbine  blades  on  each  disc  are 
adapted  to  the  increasing  volume  of  the  steam,  as  it  expands 
from  an  absolute  pressure  of  115  pounds  per  square  inch  to  an 
absolute  pressure  of  one  pound  per  square  inch.  The  first 
six  discs,  which  are  each  15  inches  in  diameter,  are  designed 
to  expand  the  steam  to  about  atmospheric  pressure,  the  re- 
mainder of  the  expansion  being  performed  in  passing  the  sev- 


PROBLEMS,  NOTES  AND  SKETCHES.  59 

enth  disc,  which  is  26^  inches  in  diameter,  and  has  (unlike  the 
other  six)  a  double  series  of  rings  of  blades,  one  series  on  each 
side,  through  which  the  steam  flows  in  parallel.  The  height  to 
which  the  turbine  blades  project  above  the  discs  in  which  they 
are  secured,  varies  from  j\  inch  to  i  inch.  The  whole  number 
of  rings  of  moving  blades,  in  the  machine  tested,  was  35.  The 
blades  are  made  of  strong  sheet  brass  and  show  no  sign  of  wear, 
after  continued  use.  Steam  enters  the  turbine  case  at  one  end 
through  a  double-beat  valve,  and,  after  passing  the  successive 
turbine  discs,  is  discharged  to  a  condenser. 

The  longitudinal  pressure  on  the  turbine  shaft,  due  to  the  one- 
sided character  of  the  turbine  discs,  is  taken  up  by  a  special  form 
of  thrust  bearing.  This  thrust  bearing,  like  the  main  bearings, 
runs  in  a  bath  of  oil. 

The  governing  of  the  machine  was  accomplished  as  follows: 
Steam  was  admitted  to  the  turbine  in  a  series  of  gusts,  by  the 
periodic  opening  and  closing  of  the  double-beat  lift  valve.  This 
valve  was  operated  by  means  of  a  steam  relay,  in  mechanical 
connection  with  the  turbine  shaft,  so  that  the  valve  was  opened 
regularly,  once  in  every  28  revolutions  of  the  shaft.  The  dura- 
tion of  each  gust  was  controlled  by  an  electric  solenoid,  which 
was  connected  as  a  shunt  to  the  field  magnets,  but  was  com- 
pounded so  as  to  keep  the  voltage  constant.  The  effect  was 
that  at  full  load  the  gusts  became  blended  into  an  almost  con- 
tinuous blast,  the  lift  valve  closing  only  momentarily,  or  not  at 
all,  in  each  of  the  periodic  movements.  Under  any  lighter  load, 
each  interval  of  admission  alternated  with  an  interval,  during 
which  the  steam  was  entirely  shut  ofif.  The  action  of  this  gov- 
ernor was  most  satisfactory.  The  speed  was  maintained  constant, 
and  there  was  no  variation  of  voltage,  sensible  on  a  voltmeter. 

In  De  Laval's  turbine,  the  vanes  are  concave  and  are  cut  on 
the  periphery  of  a  thick  disc,  a  band  being  afterwards  shrunk  on. 
The  nozzle  is  directed  against  the  plane  of  the  disc  at  a  small 
angle  and  tangentially  against  the  circumference  of  the  mean 
periphery  of  the  blades. 

The  action  is  described  as  follows: 

The  steam  expands  to  the  back  pressure,  in  the  nozzle,  before 
reaching  the  blades.  This  expansion  is  caused  by  making  the 
sides  of  the  nozzle  diverging.  The  specific  volume  is  thereby 
increased.  As  it  passes  on,  the  nozzle  is  again  contracted,  its 
velocity  is  increased,  and  thereby  its  momentum  is  increased. 


6o  MARINE  engines: 

Steam,  at  a  pressure  of  75  pounds,  discharging  at  a  pressure  of 
1.5  pounds,  moves  at  a  velocity  of  4600  feet  per  second.     The 

energy, .  ^vill  be  large,  although  the  density  will  be  small. 

The  Laval  turbine  differs  from  all  others  in  that  the  full  ex- 
pansion of  the  steam  takes  place  before  reaching  the  blades,  as 
already  described,  the  full  amount  of  statical  energy  being  con- 
verted into  dynamical.  Also,  other  makers  have  tried  to  reduce 
the  number  of  revolutions  in  their  machines,  while  in  the  Laval 
this  has  not  been  the  case.  A  5  H.  P.  Laval  turbine,  4"  in 
diameter,  makes  30,000  revolutions  per  minute;  one  of  50  H.  P., 
12"  diam.,  16,000  revs.;  and  one  of  100  H.  P.,  20"  diam., 13,000 
revs.  These  high  speeds  are  obtained  without  being  accompa- 
nied by  vibration  owing  to  the  adoption  of  a  flexible  spindle,  to 
which  the  turbine  is  attached.  The  speed  is  reduced,  by  gearing, 
down  to  a  suitable  degree  for  direct  driving  of  dynamos  or  other 
machinery. 

A  number  of  nozzles  discharge  steam  against  the  blades  in  the 
same  wheel  and  the  machine  is  governed  by  an  automatic  ar- 
rangement which  cuts  ofT  a  part  of  these. 

There  would  seem  to  be  no  limit  to  the  steam  pressure  that 
can  be  used  with  this  machine.  Mons.  de  Laval  equips  his  tur- 
bines W'ith  a  special  form  of  steam  generator  that  supplies  steam 
of  from  50  to  220  atmospheres.  The  Engineer  of  Aug.  12,  1898, 
describes  a  plant  of  this  character  which  was  installed  at  the 
Stockholm  Exhibition.  It  says:  "The  steam  consumption  of 
a  turbine  of  100  horse  power  was  17.38  poimds  per  effective 
electrical  horse  power.  For  a  steam  turbine  of  300  horse  power 
under  the  same  conditions,  the  steam  consumption,  it  is  stated, 
would  be  12.54  poimds,  and  in  fact  it  is  hoped  to  reach  a  con- 
sumption of  y.j  pounds  per  effective  electrical  horse  power  for 
a  turbine  of  this  size." 

In  all  turbines  the  steam  does  its  work  by  impact  on  the  tur- 
bine blades  and  economy  is  effected  by  the  great  range  of  ex- 
pansion, which  is  carried  to  about  one  pound  above  the  exhaust 
pressure. 

The  steam  turbine  possesses  peculiar  advantages  for  driving 
dynamos,  (i)  It  may  be  directly  connected  to  high  speed  dyna- 
mos, nmning  from  2000  to  2500  revolutions  per  minute.  (2)  It 
is  much  cheaper,  lighter,  and  takes  up  much  less  space.  (3) 
There  is  a  complete  absence  of  vibration,  W'hich   simplifies  the 


PROBLEiMS,    NOTES    AND    SKETCHES.  6l 

fitting  of  a  proper  foundation  and  renders  it  unnecessary  to  fit 
strong  holding  down  bolts.  (4)  Internal  lubrication  is  unneces- 
sary and  superheated  steam  may  be  used  without  injury,  thus 
promoting  the  more  efficient  working  of  the  engine.  (5)  It  is 
more  economical  under  the  variable  loads  to  which  dynamos  are 
subject. 

An  extended  article  on  the  theory  of  the  steam  turbine,  by 
■M.  K.  Sosnowski,  will  be  found  in  the  American  Engineer  and 
R.  R.  Journal.  September,  1895,  p.  405,  cf  scq-  (In  N.  A.  Ubrary.) 
Other  references,  from  which  these  notes  are  compiled  are  as 
follows:  The  Engineer,  Oct.  11,  1895.  p.  358;  Electrical  Engi- 
neer, Nov.  II,  1897.  p.  449;  Engineering,  Xov.  26,  1897,  p.  644; 
Journal  American  Society  of  Xaval  Engineers,  A'^ol.  \\,  p.  889. 

The  Turbiiiia. 

The  following  information  and  data  is  collected  from  papers 
read  before  the  Institute  of  Xaval  Architects  and  the  Institution 
of  Civil  Engineers,  by  Hon.  Charles  A.  Parsons.  (Journal  Am. 
Soc.  Xaval  Engrs.,  Alay  and  August,  1897.) 

In  April,  1897,  it  was  estimated  that  the  total  I.  H.  P.  of  steam 
turbines,  at  work  in  England,  exceeded  30,000.  A  steam  con- 
sumption of  14  pounds  per  I.  H.  P.  has  been  ascertained,  for 
engines  of  200  I.  H.  P.,  and  a  still  lower  consumption  is  shown 
by  larger  engines. 

In  January,  1894.  a  syndicate  was  formed  to  test  thoroughly  the 
application  of  the  steam  turbine  to  marine  propulsion,  and  a  boat 
was  designed  for  the  purpose.  The  Turbinia.  as  the  boat  was 
named,  is  100  feet  in  length.  9  feet  beam,  3  feet  draft  amidships, 
and  445^  tons  displacement.  The  original  turbine  engine  in 
her  was  designed  to  develop  upwards  of  1500  actual  horse  power 
at  a  speed  of  2500  revolutions  per  minute. 

The  compound  steam  turbine,  fitted  in  her,  consists  of  a  series 
of  steam  turbines,  set  one  after  another  on  the  same  axis,  so  that 
each  turbine  takes  steam  from  the  preceding  one  and  passes  it  on 
to  the  succeeding  one.  Each  turbine  of  the  set  consists  of  a 
ring  of  fixed  blades,  called  guides,  fixed  to  the  casing,  and  also 
a  ring  of  moving  blades,  attached  to  the  shaft  The  steam  from 
the  steam  pipe,  entering  all  around  the  shaft,  passes  through 
the  first  set  of  guides,  then  through  the  first  set  of  moving 
blades,  then  through  the  second  set  of  guides,  then  through  a 
second  set  of  moving  blades,  and  so  on  through  the  complete 


62  MARINE    engines: 

turbine  motor.  The  blades  are  carefully  shaped  as  in  water  tur- 
bines, and  the  action  of  the  steam  in  each  turbine  of  the  set  is 
similar  to  that  of  water  in  the  water  turbine. 

Steam  is,  however,  an  expansive  fluid,  and  though  its  action 
in  each  individual  turbine  is  approximately  as  if  the  fluid  was 
inelastic,  yet  a  small  increment  of  volume  takes  place  at  each 
passage  through  the  blades,  and  the  expansion  going  on  at  some- 
thing like  geometric  ratio  at  each  of  the  numerous  successive 
turbines,  soon  assumes  large  proportions.  Ratios  of  expansion 
of  fifty  up  to  one  hundred  or  even  two  hundred  fold  are  common 
in  one  single  compound  turbine  of  the  condensing  type — a  com- 
mon notable  feature  in  turbine  practice  being,  that  high  expan- 
sion ratios  and  very  large  volumes  can  be  economically  dealt 
with,  without  necessarily  increasing  the  size  and  weight  of  the 
engine  to  any  large  extent.  What  is  perhaps  more  important, 
and  gives  the  turbine  a  special  advantage  over  ordinary  engines, 
is  that  practically  no  increase  in  frictional  resistances  is  incurred 
by  arranging  for  the  extra  expansion,  and  exceptional  economy 
in  steam  is  thereby  realized. 

The  boiler  is  of  the  water  tube  type  for  225  pounds  per  square 
inch  working  pressure,  with  large  steam  space,  and  large  return 
water  legs,  and  with  a  total  heating  surface  of  1 100  square  feet  and 
a  grate  surface  of  42  square  feet;  two  firing  doors  are  provided, 
one  at  each  end.  The  stokeholds  are  closed,  and  the  draft  fur- 
nished by  a  fan  coupled  directly  to  the  engine  shaft.  The  con- 
denser is  of  large  size,  having  4200  square  feet  of  cooling  sur- 
face; the  circulating  water  is  fed  by  scoops,  which  are  hinged 
and  reversible,  so  that,  a  complete  reversal  of  the  flow  of  water 
can  be  obtained  should  the  flow  of  water  be  choked.  The  auxil- 
iary machinery  consists  of  main  air  pvnnp  and  spare  air  pump, 
main  and  spare  feed  pumps,  main  and  spare  oil  pumps,  also  the 
usual  bilge  ejectors.  No  distilling  apparatus  is  fitted.  The 
fresh  water  tank  and  hot  well  contain  about  250  gallons. 

The  approximate  weights  are: 

Main  engines 3  tons   13  cwt. 

Total  weight  of  machinery  and  boilers, 

screws  and  shafting,  tanks,  etc 22  tons. 

Weight  of  hull,  complete 15  tons. 

Coal  and  water 7  tons   10  cwt. 

Total  displacement 44^  tons. 


PROBLEMS,  NOTES  AND  SKETCHES.  63 

Trials  were  made  with  screws  of  variotts  patterns,  but  the  re- 
sults were  unsatisfactory,  and  it  was  apparent  that  a  great  loss 
of  power  was  taking  place  in  the  screw.  In  the  meantime  trials 
of  H.  M.  S.  Daring  had  taken  place,  which  had  called  attention 
to  the  phenomena  of  cavitation. 

To  investigate  the  question  of  cavitation,  a  spring  torsional 
dynamometer  was  constructed,  and  fitted  between  the  engine  and 
screw  shaft,  measuring  the  actual  torque  transmitted.  The  meas- 
urements conclusively  proved  that  the  cause  of  failure  lay  en- 
tirely in  the  screws,  and,  with  the  object  of  further  investigating 
the  character  of  this  waste  of  power,  a  series  of  experiments  was 
made  with  model  two-bladed  screws  of  2  inches  diameter,  re- 
volved in  a  bath  of  water  heated  to  within  a  few  degrees  of  the 
boiling  point,  and,  in  order  that  the  model  screw  should  produce 
analogous  results  to  the  real  screw,  it  was  arranged  that  the 
temperature  of  the  water  and  the  head  of  water  above  the  pro- 
peller, as  well  as  the  speed  of  revolution,  should  be  such  as  to 
closely  resemble  the  actual  conditions  and  forces  at  work  in  the 
real  screw,  the  object  in  heating  the  water  being  to  obtain  an  in- 
creased vapor  pressure  from  the  water  so  as  to  permit  a  repre- 
sentation of  the  conditions  with  a  more  moderate  and  convenient 
speed  of  revolution  than  would  otherwise  have  been  necessary. 

The  screw  was  illuminated  by  light  from  an  arc  lamp  reflected 
from  a  revolving  mirror  attached  to  the  screw  shaft,  which  fell 
on  it  at  one  point  only  of  the  revolution,  and  by  this  means  the 
shape,  form,  and  growth  of  the  cavities  could  be  clearly  seen 
and  traced  as  if  stationary.  It  appeared  that  a  cavity  or  blister 
first  formed  a  little  behind  the  leading  edge,  and  near  the  tip  of 
the  blade;' then,  as  the  speed  of  revolution  was  increased,  it  en- 
larged in  all  directions  until,  at  a  speed  corresponding  to  that 
in  the  Turbinia's  propeller,  it  had  grown  so  as  to  cover  a  sector 
of  the  screw  disc  of  90°.  When  the  speed  was  still  further  in- 
creased, the  screw,  as  a  whole,  revolved  in  a  cylindrical  cavity, 
from  one  end  of  which  the  blades  scraped  off  layers  of  solid  water, 
delivering  them  on  to  the  other.  In  this  extreme  case  nearly  the 
whole  energy  of  the  screw  was  expended  in  maintaining  this 
vacuous  state.  It  also  appeared  that  when  the  cavity  had  grown 
to  be  a  little  larger  than  the  width  of  the  blade,  the  leading  edge 
acted  like  a  wedge,  the  forward  side  of  the  edge  giving  negative 
thrust. 


64  MARINE    engines: 

From  these  experiments  it  would  appear  that  in  aU  screws,  of 
Avhatever  sHp  ratio,  there  will  be  a  limiting  speed  of  blade,  de- 
pending upon  the  slip  ratio  and  the  curvature  of  the  back — in 
other  words,  on  the  slip  ratio  and  thickness  of  blade ;  beyond  this 
speed  a  great  loss  of  power  will  occur;  and  that  should  the  speed 
of  ship  be  still  further  increased,  the  adoption  of  somewhat  larger 
pitch  ratios  than  those  at  present  usual  will  be  found  desirable. 

Following  these  experiments  the  single  compound  turbine  en- 
gine was  removed  from  the  boat  and  replaced  by  three  separate 
compound  turbines,  directly  coupled  to  three  screw  shafts,  the 
turbines  working  in  series  on  the  steam,  being  the  high  pressure, 
intermediate,  and  low  pressure,  and  designed  for  a  complete  ex- 
pansion of  the  steam  of  one  hundred  fold,  each  turbine  exerting 
approximately  one-third  of  the  whole  power  developed,  the  three 
new  screw  shafts  being  of  reduced  scantling.  Each  shaft  carries 
three  two-bladed  screws,  18  inches  in  diameter,  making  nine  in 
all,  thus  greatly  increasing  the  screw  surface.  These  shafts  are 
slightly  inclined,  by  which  the  after  screws  are  caused  to  work 
in  water  that  is  partially  undisturbed. 

By  these  changes  the  trouble  from  cavitation  was  obviated,  and 
the  power  delivered  to  each  screws  shaft  was  reduced  to  one-third, 
while  the  division  of  the  engine  into  three  was  favorable  to  the 
compactness  and  efficient  working  of  the  turbines.  The  total 
weight  of  engines  and  the  speed  of  revolution  remained  the  same 
as  before.  The  effect  on  the  screws  was  to  reduce  their  scant- 
lings and  to  bring  their  conditions  of  working  closer  to  those  of 
ordinary  practice.  The  thrust  of  the  propellers  is  balanced  by 
steam  pressure  in  the  motors,  no  ordinary  thrust  bearings  being 
fitted. 

At  all  speeds  the  boat  travels  w'ith  an  almost  complete  absence 
of  vibration,  and  the  steady  flow  of  steam  to  the  motors  may 
have  some  influence  on  priming,  no  sign  of  it  having  occurred. 
The  boat  has  been  run  at  nearly  full  speed  in  rough  water,  and 
no  evidence  of  gyroscopic  action  has  been  observable,  though 
such  a  result  would  be  anticipated  from  the  known  small  amount 
of  these  forces  under  actual  conditions  in  other  boats. 

Another  report  of  the  trials  says  that,  when  going  full  speed, 
the  writer  could  not  tell,  by  placing  his  hand  on  it,  whether  the 
motor  was  going  or  not;  and  the  only  vibration  was  due  to  the 
air  pump,  which  was  driven  by  a  reciprocating  engine. 


PROBLEMS,  NOTES  AND  SKETCHES.  65 

The  oiling  of  the  main  engines  is  carried  on  automatically, 
under  a  pressure  of  lo  pounds  per  square  inch,  by  a  small  pump 
worked  ofif  the  air  pump  engine;  a  small  independent  duplex  oil 
pump  is  also  fitted  as  a  standby.  The  main  engines  require  prac- 
tically no  attendance,  beyond  the  regulation  of  a  small  amount  of 
live  steam,  to  pack  the  glands  and  maintain  a  good  vacuum. 

The  advantages  claimed  for  the  compound  steam  turbine,  over 
ordinary  engines,  for  marine  use,  are  as  follows: 

1.  Increased  speed. 

2.  Increased  economy  of  steam,  due  to  the  high  rate  of  ex- 
pansion. 

3.  Increased  carrying  power  of  vessel. 

4.  Increased  facilities  for  navigating  shallow  waters. 

5.  Increased  stability  of  vessel. 

6.  Increased  safety  of  the  machinery  for  war  purposes. 

7.  Reduced  weight  of  the  machinery. 

8.  Reduced  space  occupied  by  machinery. 

9.  Reduced  initial  cost. 

10.  Reduced  cost  of  attendance  on  machinery. 

11.  Diminished  cost  of  repairs  of  machinery. 

12.  Absence  of  vibration. 

13.  Reduced  size  and  weight  of  screw  propellers  and  shafting. 

Mr.  Parsons  mentions  no  disadvantages  in  this  connection,  but 
the  principal  one  lies  in  the  difficulty  of  reversing  the  motion  of 
the  vessel.  In  the  Turbinia,  this  is  accomplished  by  having  a 
small  turbine  on  the  centre  shaft,  with  vanes  in  the  reverse  di- 
rection to  those  of  the  main  engines,  which  can  drive  the  boat 
sternward  at  a  very  low  speed. 

It  is  further  claimed  by  Mr.  Parsons.  ''  that  the  substitution  of 
steam  turbines  in  place  of  reciprocating  engines,  in  vessels  of  the 
largest  size,  and  of  fast  or  moderately  fast  speeds,  presents  ad- 
vantages greater  than  those  which  have  been  realized  in  the  little 
vessel  Turbinia,  and  it  may  be  roughly  stated  that  for  such  ves- 
sels the  speed  of  rotation  would  be  slow,  from  250  to  500  revo- 
lutions per  minute,  and  the  relative  simplicity  of  these  engines 
would  become  still  more  marked  than  is  the  case  in  the  Tur- 
binia's  engines,  indicating  2400  I.  H.  P.,  and  giving  her  a  ve- 
locity of  35  knots,  or  over  40  miles  per  hour,  with  an  expenditure 
of  steam  of  14  pounds  per  I.  H.  P.  per  hour." 
5 


66  MARINE  engines: 

Trials. — The  most  successful  trials,  to  date  (Sep.  1898),  of 
which  accounts  have  been  published,  were  made  in  April  1897. 
The  mean  of  two  consecutive  runs  gave  a  speed  of  31.01  knots, 
the  mean  revolutions  of  the  engines  being  2100  per  minute,  the 
fastest  run  being  at  the  rate  of  32.61  knots. 

The  utmost  horse  power  recjuired  to  drive  the  boat  at  the  speed 
of  31.01  knots  is  945.  as  calculated  from  experiments  on  a  model 
made  at  Heaton  Works,  on  the  method  of  the  late  Mr.  William 
Froude. 

Assuming  the  rate  of  thrust  horse  power  to  indicated  horse 
power  to  be  60  per  cent,  (which  appears  to  be  the  ascertained 
ratio  for  torpedo  boats  and  ships  of  fine  lines),  the  equivalent 
I.  H.  P.,  for  31.01  knots,  is  1576. 

The  consumption  of  steam  at  31.01  knots  was  approximately 
25,000  pounds  per  hour;  or,  15.86  pounds  per  I.  H.  P.  per  hour. 
It  should  be  observed  that  the  assumption  of  the  thrust  horse 
power  being  60  per  cent,  of  the  I.  H.  P.  presupposes  that  the 
propellers  are  of  the  best  form  obtainable;  and,  should  those 
fitted  be  superseded  by  others  of  higher  efficiency,  as  is  possible, 
then  the  figures  of  consumption  per  L  H.  P.  will  be  correspond- 
ingly improved  and  the  speed  of  the  boat  increased. 

At  present  the  inability  to  reverse  quickly  is  the  obstacle  to 
fitting  the  turbine  in  torpedo  boats.  It  is  reported,  however,  that 
two  torpedo-boat  destroyers  are  now  (September  1898)  being 
built  at  Wallsend  on  the  Tyne,  which  are  to  be  fitted  with  tur- 
bines. A  speed  of  forty  knots  is  expected.  Thirty-five  knots 
when  going  ahead  and  seventeen  knots  when  backing  are  guar- 
anteed. One  of  these  boats  is  for  the  British  government  and 
the  other  for  a  foreign  government. 

THE  THEORY  OF  CAVITATION. 

Art.  22. 

Extracts  from  a  paper  read  at  the  International  Congress  of 
Naval  Architects  and  Marine  Engineers,  by  Sydney  W.  Barnaby, 
Journal  Am.  Soc.  Naval  Engrs.,  November,  1897,  p.  678: 

If  a  cavity  be  formed  in  any  manner  in  the  interior  of  a  mass 
of  water  it  will  tend  to  become  filled  with  water  vapor  and  with 
any  air  which  might  be  in  solution,  since  ebulition  takes  place  at 
ordinary  temperatures  in  a  vacuum. 


PROBLEMS,  NOTES  AND  SKETCHES.  6/ 

The  trials  of  the  Daring  disclosed  the  following  facts:  With 
a  pair  of  three-bladed  screws  6.16  feet  in  diameter,  9  feet  mean 
pitch,  and  8.92  square  feet  developed  surface,  the  Daring  attaine.d 
a  speed  of  24  knots  with  3700  I.  H.  P.,  the  screws  making  30 
per  cent.  slip.  With  a  pair  of  screws  of  the  same  diameter, 
and  practically  the  same  mean  pitch,  but  with  a  surface  of  12.9 
square  feet — an  addition  of  45  per  cent,  to  the  surface — the  same 
speed  was  obtained  with.  650  less  horse  power,  and  with  17^ 
per  cent,  slip  instead  of  30  per  cent.  The  number  of  revolutions 
required  for  24  knots  with  the  screws  of  small  area  sufificed  to 
drive  the  vessel  at  28.4  knots  when  the  blade  area  was  increased. 
The  vibration  was  unprecedented  and  dangerous  with  the  narrow 
blades ;  it  was  of  quite  a  normal  and  unimportant  character  when 
the  blades  were  widened. 

In  order  to  arrive  at  a  clear  understanding  of  what  is  believed 
to  take  place,  it  is  necessary  to  distinguish  between  the  two  cases 
— first,  that  of  a  propeller  drawing  air  from  the  surface;  and  sec- 
ond, that  of  the  formation  of  cavities  when  the  propeller  is  sub- 
merged. The  effect  upon  the  thrust  of  a  fast-running  screw 
when  the  blades  break  the  surface  of  the  water  or  when  air  pene- 
trates from  the  surface  is  well  known.  Under  such  conditions 
the  velocity  under  which  water  can  flow,  due  to  gravity  at  a 
depth  h  below  the  surface,  is  equal  \'  2gh,  and  amounts,  for  ex- 
ample, to  only  Syz  knots  at  a  depth  of  one  meter. 

If  the  velocity  with  which  a  portion  of  the  blade  situated  at  a 
depth  h  moves,  is  less  than  ^  2gh,  the  water  will  keep  in  contact 
with  it,  even  if  the  blade  break  the  surface,  and  there  will  be  no 
loss  of  efificiency. 

When  the  screw  is  sulBciently  submerged  to  exclude  air  from 
the  surface,  the  rate  at  which  the  water  can  be  accelerated  is  very 
much  greater.  This  can  be  illustrated  as  follows:  Water  will 
flow  from  a  tank  through  an  orifice  discharging  into  the  open 
air  at  a  velocity  depending  upon  the  depth  of  the  orifice  below  the 
surface  of  the  water  in  the  tank. 

It  will  flow  through  the  same  orifice  into  the  exhausted  re- 
ceiver of  an  air  pump  at  a  much  higher  velocity,  depending  upon 
the  degree  of  exhaustion  in  the  receiver.  The  velocity  in  the 
latter  case  will  be  that  due  to  the  head  of  the  water  plus  the 
difference  between  the  pressure  of  the  atmosphere  and  that  in 
the  exhausted  receiver.     Similarlv,  the  velocitv  with  which  water 


68  MARINE  engines: 

can  be  made  to  flow  towards  a  submerged  screw  is  due  to  the 
head  of  water  over  the  screw^  phis  the  atmospheric  pressure,  and 
there  is  consequently  a  definite  hmit  to  the  speed  to  which  it 
can  attain. 

It  was  not  easy  to  calculate  theoretically  at  what  point  the 
breakdown  would  occur  with  a  given  propeller,  but  a  way  of 
attacking  the  problem  suggested  by  Mr.  Thornycroft  proved  to 
greatly  simplify  it,  and  to  render  its  solution  possible.  His  idea 
was  that  there  must  be  a  definite  thrust  per  sq.  inch  of  projected 
screw  surface  at  which  cavitation  commenced. 

A  screw  propels  by  putting  water  in  motion  sternwards.  It 
effects  its  object  partly  by  pushing  the  water  with  the  after  face 
of  the  blades,  and  partly  by  pulling  it  with  the  forward  face.  Im- 
agine that  we  have  replaced  the  screw  of  a  ship  by  a  disc  of  rather 
less  diameter  than  the  screw,  and  that,  instead  of  revolving  the 
screw  shaft,  we  push  the  shaft  and  disc  sternwards  at  such  a  speed 
that  the  momentum  of  the  water  moved  by  the  disc  is  equal  to 
the  sternward  momentum  of  the  water  put  in  motion  by  the 
screw.  The  propelling  efifect  would  be  the  same  as  that  of  the 
screw,  or  nearly  so  if  the  movement  is  confined  to  the  length  of 
the  screw,  and  so  far  as  the  action  between  the  forward  face  of 
the  screw  blades  and  the  contiguous  water  is  concerned,  which 
is  what  I  wish  to  illustrate,  the  action  of  the  disc  afifords  a  suffi- 
ciently close  analogy.  As  the  disc  moves  sternwards,  it  puts 
water  in  motion  not  only  astern  of  it  but  also  ahead  of  it.  There 
being  no  air  ahead  of  the  water  and  the  front  face  of  the  disc, 
a  pull  can  be  exerted  upon  the  water,  which  is  forced  to  follow 
the  disc  in  the  same  manner  that  water  is  forced  to  follow  the 
plunger  of  a  pump. 

But  the  pull  which  can  be  thus  exerted  by  the  disc  is  limited. 
At  a  little  beneath  the  surface  of  the  water,  if  the  tension  ex- 
ceeds 15  pounds  per  square  inch  (one  atmosphere),  the  surfaces 
of  the  disc  and  adjacent  water  are  torn  asunder,  and  the  cavity 
is  formed  between  them. 

As  but  a  little  more  than  half  of  the  total  acceleration  im- 
parted to  the  water  by  a  screw  is  estimated  to  be  produced  by 
the  suction  of  the  forward  surface,  it  might  be  supposed  that  a 
total  thrust  approaching  to  30  pounds  per  square  inch  (two  at- 
mospheres) might  be  obtained,  but  it  appears  that  rupture  occurs 
at  parts  of  the  screw  surface  long  before  the  mean  thrust  per 


PROBLEMS,    NOTES   AND    SKETCHES.  69 

square  inch  of  the  whole  surface  reaches  this  amount.  This  is 
probably  accounted  for  by  the  fact  that  the  thrust  of  portions  of 
the  screw  blade  near  the  circumference  is  much  greater  than  at 
portions  near  the  boss. 

By  plotting  the  results  of  a  progressive  trial  carried  beyond 
the  speed  at  which  cavitation  commenced,  we  were  able  to  note 
the  point  at  which  the  first  indication  of  failure  appeared.  It  is 
not  marked  by  a  sudden  change,  but  by  a  flexure  in  the  curve  of 
slip,  which  commences  to  rise  rapidly  when  the  critical  speed  is 
reached. 

The  total  thrust  of  the  screw  at  this  speed,  divided  by  its  pro- 
jected blade  area,  gave  a  thrust  of  11 34  pounds  per  square  inch 
(0.75  atmosphere),  which  is,  therefore,  about  the  maximum  thrust 
which  can  be  obtained  from  a  screw  working  efficiently  at  a  depth 
below  the  surface  of  1 1  inches,  which  was  the  immersion  of  the 
tips  of  the  blades  in  the  Daring.  The  figure  should  vary  slightly 
with  the  pitch  ratio,  being  less  if  the  latter  is  high,  since  the 
ratio  which  the  suction  thrust  bears  to  the  whole  thrust  varies 
with  the  pitch  ratio,  but  the  variation  is  so  small  as  to  be  negli- 
gible. For  every  additional  foot  of  immersion,  the  total  thrust 
per  square  inch  may  be  increased  by  ^  of  a  pound.  3 

Problems.— (P.  301,  S.  &  O.)  LH.T. 

80.     The  following  data  are  from  trials  of  the  U.  S.  S.  York-        2,  -    — 
tow^n : 


Speed  in  knots 
per  hour. 

I.H.  P. 

Revoluiions 
per  minute. 

Displacement. 

16.62 

3570 

161 

1700  tons. 

14.78 

2325 

140 

1700  tons. 

Required  the  I.  H.  P..  and  the  number  of  revolutions  per  min- 
ute to  drive  this  ship  at  a  speed  of  10  knots. 

81.  How  many  revolutions  and  what  I.  H.  P.  would  be  re- 
quired to  drive  the  Yorktown  18  knots  per  hour? 

82.  The  design  of  the  New  York  is  for  a  speed  of  20  knots 
with  16,500  I.  H.  P.,  and  a  displacement  of  8150  tons. 

What  I.  H.  P.  would  this  ship  require  to  drive  it  21  knots? 
Keeping  the  same  L  H.  P..  what  amount  of  weight  must  be 
removed  so  that  it  will  make  22  knots? 

83.  A  400-ton  ship  has  a  maximum  speed  of  10  knots.     Sup- 


70  MARINE  engines: 

pose  that  it  take  on  board  loo  tons  of  coal,  what  speed  can  then 
be  made? 

84.  If  at  the  maximum  speed  of  the  Yorktown  (see  Prob.  80), 
2.3  pounds  of  coal  per  I.  H.  P,  per  hour  is  required,  and  at  10 
knots  per  hour  only  1.8  pounds,  what  distance  can  be  covered  on 
a  coal  supply  of  100  tons  at  the  maximum  and  at  the  reduced 
speeds? 

85.  A  ship  whose  displacement  is  400  tons  makes  10  knots 
with  300  I.  H.  P. 

How  much  would  it  be  necessary  to  lighten  the  ship  so  that 
with  the  same  I.  H.  P.  it  may  make  11  knots? 

86.  What  is  the  most  economical  speed  for  a  steamer  steam- 
ing against  a  current  running  a  knots  per  hour? 

Solution  of  Question  86. 

Let  C  =  Coal  consumed  per  day  or  hour. 

x  =  Speed  of  the  ship  through  the  water. 

.r  —  a  =  Speed  of  the  ship  over  the  ground. 

C 

=  Cost  in  coal  per  knot  over  the  ground. 

X  —  a 

Making  this  a  minimum  will  give  the  most  economical  speed 
against  the  current. 

The  coal  expended  varies  as  the  cube  of  the  speed,  since  this 
amount  is  nearly  proportional  to  the  I.  H.  P.     Therefore: 

Let  C  =  Kx^;  where  K  is  a.  constant.    "Then 

C  Kx^  .  ,         .    , 

■  —  • .     Dififerentiate  this  equation,  and  we  find: 

X  —  a      X'  —  a 

S T- —  =  o  •      Solvmg 

[x  —  ay 

X  r=  fa. 

EXPLANATION  OF  THE  METHOD  OF  COMPLETING 
THE  CURVE  OF  INDICATED  THRUST. 

Art.  23.— (P.  304,  S.  &  O.) 

'■  The  curve,  as  fixed  by  the  data,  terminates  at  some  moder- 
ate speed;  say  3,  4  or  5  knots.  It  is  known  that  with  tolerably 
well  shaped  ships  the  resistance  due  to  such  moderate  speeds  as 


PROBLEMS,  NOTES  AND  SKETCHES.  7I 

these  consists  almost  solely  of  surface  friction;  which,  as  experi- 
ments have  shown,  varies  nearly  as  the  1.87  power  of  the  speed, 
with  perhaps  a  very  small  residue,  or  excess  of  resistance,  ap- 
parently proportional  to  the  square  of  the  speed.  As  this  resi- 
due is  very  small  indeed,  we  may  assume  that  the  whole  resist- 
ance, below  3  or  4  knots,  is  as  the  power  1.87  of  the  speed." — 
(W.  Froude.  Transactions  of  the  Institute  of  Naval  Architects, 
Vol.  XVIL,  1876,  p;  170.) 

Equation  to  curve  is  y  =  ax'^-^''+  c  (l) 

Let  x-^  and  \\  be  coordinates  of  P,  then 

3'o  =  c  —  \\  —  a.r,i-8'  (2) 

d_y 
Differentiating  (i)  ,  j- =  1.87  ax^-^' . 

Equation  to  tangent  at  P  is 

3 —  3.^  =  1 .87  aA-o-8'(.i-  — .r,)  (3) 


In  (3)  let  3'  =  c  =  yo,  then 

3'i  —  a.i-ii-s^—  3'i  =  1.87  ax^-^^x  —  x^), 


from  which  x 


1.87 
OR' _o.S7 
^^'  OQ^YJj' 

Art.  24.— (P.  338,  S.  &  O.) 

The  main  points  of  construction  of  the  indicators  shown  in 
Figs.  26  and  2"/  are  almost  the  same  as  those  described  on  pages 
336-338  of  Sennett  and  Oram. 

A  set  of  indicators  is  always  supplied  to  the  ships  of  our  navy, 
and  reducing  gears  are  fitted  to  each  cylinder,  so  that  the  indi- 
cator has  only  to  be  carefully  and  correctly  placed  on  the  indi- 
cator cock,  the  string  attached  and  the  card  from  each  end  of  the 
cylinder  taken. 

Before  attaching  the  indicator,  which  is  kept  in  its  box  in  the 
storeroom,  take  the  caps  off  the  indicator  cocks  on  the  cylinder 
and  blow  steam  through  to  clear  and  warm  up  the  cocks  and  con- 
necting pipes. 

Place  the  taper  nozzle  in  the  mouth  of  the  cock  and  set  up  on 
the  jam  nut  and  attach  the  indicator  firmly  with  the  cord  pulley 


72 


MARINE    engines: 


leading  fair  to  the  point  of  attachment  on  the  reducing  motion. 
A  strong  inelastic  cord,  with  an  attached  hook,  is  wound 
around  the  bottom  of  the  paper  drum,  and  as  the  drum  is  re- 
volved, by  this  cord,  it  should  not  come  up  against  its  stops. 
When  certain  that  this  is  the  case  and  that  everything  is  work- 
ing smoothly,  stop  the  drum  with  the  pawl,  bend  the  indicator 
card  around  the  top  of  the  drum  and,  holding  the  ends  together, 
slip  them  down  between  the  clips,  leaving  the  surface  of  the  card 
smooth  and  the  ends  square. 


Fig.  37. — Section  of 
Indicator. 


Fiiir.  36. — Indicator. 


Turn  steam  on  slowly,  to  warm  up  the  indicator  and  blow  it 
free  of  water,  and  when  this  is  done  shut  off  the  steam  and  let 
the  pencil  trace  the  atmospheric  line  on  the  card.  Turn  the 
steam  on  full  and  bring  the  pencil  point  lightly  against  the  card, 
tracing  a  light  single  line  during  one  revolution  of  the  engine. 
Do  this  for  each  end  of  the  cylinder,  then  remove  the  card  and 
write  the  required  data  on  the  blank  spaces  on  its  back. 

When  cards  have  been  taken  from  all  the  cylinders,  remove  the 
indicators,  wipe  them  dry  and  clean,  then  oil  the  pistons  and 


PROBLEMS,  NOTES  AND  SKETCHES. 


73 


replace  in  the  indicator  boxes.     Screw  the  caps  on  the  cocks  and 
see  that  all  the  valves  are  closed. 

Figs.  28  and  29  show  the  back  and  front  of  the  indicator  card 
complete  and  ready  to  be  filed  away  or  sent  on  to  the  Depart- 
ment with  the  quarterly  returns. 


NOTE. 

To  FIND  THE  Mean  Effective  Pressure  of  a  Theoretical 
Indicator  Card  having  Compression  and  Clearance. 

Art.  25.-(P.  344,  S.  &  O.) 

It  is  assumed  that  both  the  expansion  and  compression  curves 
follow  the  law  pv  =^  a.  constant. 

A,  B,  C,  D,  represent  the  areas  shown  in  the  figure;  and  a,  b,  c, 
d,  e,  f,  g,  the  lengths  as  shown  on  the  theoretical  card. 

p^  =  the  mean  effective  pressure  =  the  mean  ordinate  of  the 
area  A. 

A      {A+B-\-C  -\-  D)—B—  C  —D 
Pe  =  -=  , •  (0 

From  a  previous  note  (Art.  17),  we  can  find  the  area  {A  -{-  B  -\- 
C  +  D)  and  also  that  of  B  from  the  equation  deduced  in  that 
note: 

(I  +  hyp.  log.  r) 


Area  =  p^X  -  - 


X  the  length  of  the  area.        (2) 


In  {A  -\-  B  -\-  C  -\r  D)  we  have,  from  the  figure,  p-^^  =  e;  and 

a  +  c 
— -.  ,  and  by  the  figure  also,  the  length  of  the  area  =  a  +  c. 

...     c     -» 


*-2l-*. 6 


Fig.  30. 


Bureau  of  St.  Kng'r'g.  }  y 

No.  ..r*-.'. 


FoKM  No.  r>0  D.         C  Caud 


fU.  S.  S. 
Date  and  hour, .  ^^^.  / S^  /I.fJ^  i2,/Oj^7tcy, 

Which  engine,    CL> LoS^^A^  Q.^cLi  , 

Which  cylinder  and  which  end,  r/f^..   /'^.P^. . ?koeLt 

Rovohitions    per  minute, /.t^.^rrj — 

Steam  pressure  in  boilers, by  gauge, in  lbs.,. . .  /.//r.y.i.^ 

'•        at  engine,,  "  "       ../A/iiJ^... 

'■  "        in  ..•^4-rMi^7?.  receiver,  in  lbs.,  above  a 

perfect  vacuum, .^sJ...<. 

Steam  cut-off  at '.v. of  the  stroke  from  the 

beginning  by TrTTTTl 

Position  of  link,  . . .  ..y^.£U7^^t^^. - .^ 

2  I  Opening  of  throttle- valve,  in  holes, ./.V-. .-. 

-o  'vacuum,  in  inches  of  mercury,. Tr./^.-t.. 

I    Indicated  horse  power  of  this  diagram,  ../^.^^  .^ ..^./ 
.|  I  "  "  "      of  this  cylinder,.. /  ^'J^.^^.y./^ 

Collective  I.  H.  P.  of  engine, .A  i  0  .S^.'..?.^ 

Horse  power  ipiCf^oi  aux.  machinery  in  usf>,  .oT./.  9.  :/.d 
Square  feet  of  heating  surface  in  use.  ■xI«^.9./-/j  .<?.V 

Square  feet  of  grate  surface  in  use, jC'^-/-:^.^... 

Pounds  of  coal  (  /3.ul/-Zi^ .) ,  net  weigh't,  consumed 

per  hour, '^.^ ^J .'/../. 

Speed  per  hour,  in  knots  and  tenths, r^-.^../__oL... 

Sails  .set, .??-<^r*-*?^:^ 

Wind.     Points  from  ahead, ^_ Force, ^-^ 

Sea.  "  "  "     ,.....s5.....  Kind,  ...rTTTT! 

Barometer, -^.t! .7^^  Attached  thermometer,....^^. 

Temperature  of  injection  water, i^J^^ 

"  "  discharge  water, ../.y..^.z..^.. 

"  "  feed  water, /_.<?^_^.^.. 

Draught  I  measured  at  the  c  Forward,  ...'.^.Z_-rr^.v__. 

f       J   time,  if  possible ;  J                                               ,               /e 
,^  "*  ,      )   othetTvise,  esti-  J     ...                        X?    ^H            ^ 
Vessel.    (  mated.  (  Aft,... .^.'0..-r...9. 

Slip  of  Propeller, ^.^.'..£.^..Z^ — _ 

4—162 

Fig.  28. — Front  of  Indicator  Card. 

74 


Nt 


;t^ 


hH 


^ 


Tcji 


JBoiioTTt" 


% 


Pio'.  29. — Back  of  Indicator  Card. 


75 


76 


MARINE   engines: 


Similarly,  in  the  case  of  B,  we  have  from  the  figure : 
a  ■{-  d 


P.  =  t 


.  and  the  length  of  the  area  ^=  a  -\-  d. 


Making  these  substitutions  in  (2)  we  find  the  area  {A  -\-  B  -\-  C 
+  D)  and  also  that  of  B. 

C  and  D  are  rectangles  and  their  areas  equal  their  lengths  X 
their  breadths. 

Substituting  in  (i),  p^    is  found. 

Note: — In  solving  problems  like  this,  first  draw  the  theoretical  indi- 
cator card  as  above,  and  place  all  the  known  quantities  upon  it. 

Then  by  means  of  the  equation,  pv  =  a  constant,  find  the  quantities  not 
given  and  proceed  as  shown. 


Example. 

Stroke  of  the  engine  =.  42" .  Cut-ofif  is  at  9"  from  the  begin- 
ning of  the  stroke.  Clearance,  reduced  to  equivalent  length  of 
cylinder,  is  4".  Initial  pressure  =  100  pounds.  Compression 
begins  6"  from  the  end  of  the  stroke.  Back  pressure  before  the 
compression  begins  ^15  pounds  absolute. 

Find  the  mean  efifective  pressure  on  the  piston  of  the  engine. 


Fig.  31. 


D=  15(42  — 6)  =  540. 
C  =  4  (100  —  37.5)^=250. 


PROBLEMS,  NOTES  AND  SKEICHES.  -  'J'J 

Then,  in  B,  since //'^  —  P\^'\^ 

;»;X4=  loX  15.   •••  '^'  =  37-5- 


f         ,         ,         /42  +  4'  ] 


{A^  B  +  C+  D)^\ooY. ^2-\-A    (42  +  4) 


9  +  4 
=  100  X  46  X  .642=  2953.2, 

^  =  37-5  X  ^ 6  +  ^  ^  (6  +  4) 


4 

=  37-5  X  10  X  .766  —  287.25. 
Consequently: 

^       2953.2- (287.25  +  250+  540) 

Problems. 

87.  Stroke  of  engine  =  34".  Initial  pressure  =  175  pounds 
per  square  inch.  Final  pressure  =  10  pounds  per  square  inch. 
Back  pressure  :=  3  pounds  per  square  inch.  Clearance  =  i". 
Final  pressure  of  compression  =12  pounds  per  square  inch. 
Area  of  the  piston  =:  200  square  inches.  Engine  makes  150 
revolutions  per  minute. 

Find  the  I.  H.  P.  of  the  engine.  Ans.     161.97  I-  H.  P. 

88.  Supposing  that  all  the  data  of  the  preceding  question  re- 
main the  same  except  that  the  stroke  be  changed  to  40". 

Find  the  I.  H.  P.  Ans.     194.4  I.  H.  P. 

89.  Stroke  of  engine  ^  8".  Diameter  of  the  cylinder  =  10". 
Initial  pressure  of  the  steam  =  160  pounds  per  gauge.  Ratio  of 
expansion  ^12.  Back  pressure  =  8  pounds  per  square  inch. 
Clearance  =  .4".  Compression  to  begin  at  the  middle  of  the 
stroke.     Engine  makes  250  revolutions  per  minute. 

Find  the  I.  H.  P.  Ans.     23.785  I.  H.  P. 

90.  Supposing  that  all  the  data  of  the  previous  question  re- 
main the  same  except  that  the  initial  pressure  be  100  pounds  ab- 
solute, instead  of  per  gavtge. 


78  MARINE  engines: 

Find  the  I.  H.  P.,  and  the  consequent  change  in  the  number  of 
revolutions  per  minute  that  would  necessarily  follow. 

Alls.     I.  H.  P.  =  5.208;  Revolutions  =  150.7. 

91.  Find  the  gain  in  I.  H.  P.,  if  the  engine  of  question  89 
has  a  back  pressure  of  3  pounds  instead  of  as  there  given. 

How  many  heat  units  does  this  represent? 

If  the  feed-w^ater  be  taken  from  the  hot-zuell,  how  much  has  it 
been  cooled? 

Is  there  any  gain  then  in  carrying  the  vacuum  lower? 

The  temperatures  of  steam  of  8  pounds  and  3  pounds  are 
182.92°,  and  141.62°  respectively. 

Ans.     Gain  =  11.46  I  H.  P. 

92.  Stroke  of  the  engine  ^  33".  Clearance  =  7  per  cent,  of 
the  piston  displacement.  Initial  pressure  ^  180  pounds  absolute. 
Final  pressure  =  15  pounds.  Final  pressure  of  compressions 
50  pounds.  Compression  to  continue  for  ^  of  the  stroke.  Di- 
ameter of  the  piston  =:  40",.     Revolutions  per  minute  =:  150. 

Find  the  I.  H.  P.  Ans.     1050  I.  H.  P. 

93.  If  the  clearance  of  the  engine  of  the  previous  question  be 
changed  so  that  it  is  twice  as  large,  and  the  point  of  cut-off  re- 
main the  same,  what  will  then  be  the  I.  H.  P.? 

Ans.     1610  I.  H.  P. 

94.  If  the  stroke  of  the  engine  of  question  92  be  made  40" ; 
the  other  data  remaining  the  same,  what  will  then  be  the  I.  H.  P.? 

95.  Suppose  that,  in  question  92,  the  final  pressure  of  com- 
pression =  the  initial  pressure. 

Find  the  I.  H.  P. 

NOTE. 

Water  per  I.  H.  P.  per  Hour  Accounted  for  by  the 
Indicator  Card. 

Art.  26.— (P.  352,  S.  &  O. 

The  weight  of  steam  in  the  cylinder,  at  any  instant,  can  be 
found  by  dividing  the  volume,  occupied  by  it  at  the  given  time^ 
by  the  specific  volume  of  the  steam  for  the  pressure  in  the  cylinder. 

The  pressure  is  taken  from  the  card  and  the  specific  volume 
is  either  taken   from  the  tables   or  calculated  by  the   equation 


PROBLEMS,    NOTES    AND    SKETCHES.  79 

It  is  evident  that  if  there  be  no  condensation  or  re-cvaporation, 
the  weight,  so  calculated,  would  be  the  same  for  all  points  of  the 
expansion  curve,  and  that  the  same  would  also  be  true  for  the 
compression  curve. 

The  weight  of  steam  used  by  the  engine  per  stroke  would  then 
be  the  difference  between  the  weights  calculated  for  the  pressures 
given  by  the  two  curves.  The  first  quantity  is  the  steam  in 
the  cylinder  at  the  end  of  the  stroke  and  the  second  quantity 
the  amount  of  compressed  steam  that  is  retained  in  the  cylinder 
and  which  does  not  go  to  the  condenser. 

This  difference  of  weight  per  stroke  being  multiplied  by  the 
number  of  strokes  per  hour  and  divided  by  the  I.  H.  P.  developed 
gives  the  number  of  pounds  of  water  used  per  I.  H.  P.  per  hour, 
as  accounted  for  by  the  indicator. 

In  the  theoretical  card,  the  only  points  that  we  know  in  the 
curve  are  those  of  cut-off  and  exhaust  closure,  and  these  would 
be  the  points  which  we  would  have  to  use. 

In  an  actual  card,  however,  any  points  of  the  curve  may  be 
used. 

Example. 

Find  the  number  of  pounds  of  water  per  I.  H.  P.  per  hour  ac- 
counted for  by  the  indicator,  which  is  used  by  an  engine,  the 
theoretical  card  and  other  data  of  which  are  in  the  Example  pre- 
ceding Problem  87. 

The  area  of  the  piston  =  1000  square  inches,  and  the  number 
of  revolutions  per  minute  ^  50. 

/     N       A  rr        1  •  1  (9  +  4)    X    1000 

(1)  At  cut-ori,  the  steam  occupies  a  volume  = ^ 

1728 

cubic  feet. 

The  specific  volume  of  the  steam  as  calculated  above,  or  as 
taken  from  the  tables,  for  an  initial  pressure  of  100  pounds  per 
square  inch  =  4.4  cubic  feet. 

(2)  Consequently  the  weight  of  the  steam  at  cut-off 

(9  +  4)  X  1000 

= ;z pounds. 

1728  X  4-4 

Similarly  the  weight  of  steam  in  the  cylinder  at  exhaust  clo- 

(6  -f-  4)  X  1000 

sure  = ^r-~- — p pounds,  the  specific  volume  for  steam  of 

1728  X  26.15   ^ 

15  pounds  pressure  being  26.15  cubic  feet. 


8o  MARINE  engines: 

iooof(9  +  4)    (6+4)) 

(t,)  The  difference  between  (i)  and  (2)=       -  \  > ^—^ — '-  [ 

^-^^  V  /  V  y     j^28  (    4.4        26.15  J 

is  the  weight  of  steam  used  per  stroke,  or,  expressing  the  same 

thing  differently,  it  is  the  amount  of  steam  which  the  cyHnder 

empties  into  the  condenser  at  each  stroke,  and  the  amount  which 

is  not  emptied  is  that  retained  for  compression;  this  helps  fill  the 

cylinder  when  the  fresh  steam  comes  from  the  boiler  for  the  next 

stroke. 

(4)  The  weight  of  steam  used  per  hour  r=  (3)  X  2  X  50  X  60. 

[44.6  X  ^  X  1000  X  2  X  50] 

(5)  I.  H.  P.  =    ^" 

^^^  33000 

(4) 

(6)  Therefore ^r=  the  number  of  pounds  of  water  per  I.  H.  P 

per  hour  used  by  the  given  engine,  as  accounted  for  by  the  indi- 
cator and  calculated  from  the  theoretical  indicator  card. 

METHOD  WHEN  USING  AN  ACTUAL  INDICATOR 

CARD. 

Art.  2y. — If  an  actual  card  be  used,  and  a  line,  such  as  ab,  be 
drawn,  above  the  points  of  release  and  compression  and  below 
admission,  parallel  to  the  atmospheric  line,  cutting  both  the  ex- 


Fii 


pansion  and  compression  lines  as  shown;  then  letting  the  length 
in  inches  of  the  intercept  of  the  line  ab  by  the  curves  be  x;  the 
area  of  the  card  be  A  square  inches;  the  specific  volume  be  v, 
corresponding  to  the  pressure  p  at  the  line  ab;  s  be  the  scale  of 


PROBLEMS,  NOTES  AND  SKETCHES. 


81 


the  indicator  spring;  /  be  the  length  of  the  card  in  inches;  V  be 
the  volume  of  piston  displacement  in  cubic  feet,  and  N  be  the 
number  of  revolutions  of  the  engine  per  minute. 

X       V 
The  total  water  per  hour  =  ,  X  ^    X  6o  X  2A^  (l) 


/ 

A 


X  s  X  144  rx  2/^ 


The  I.  H.  P.  of  the  cylinder 


G^) 


33000 

Dividing  (i)  by  (2),  we  have  water  per  I.  H.  P.,  per  hour  = 

13750  X  -r 
sAv 

This  formula  gives  the  water  per  I.  H.  P.  per  hour  if  the  card 
is  from  a  simple  engine.     If  from  one  cylinder  of  a  multiple  ex- 
pansion engine,  the  result  should  be  multiplied  by 
I.  H.  P.  of  cvlinder 


I.  H.  P.  of  engine 


Problems. 

96.     Find  the  number  of  poiuids  of  z^'atcr  per  I.  H.  P.  per  hour 
used  by  the  engine  of  Problem  87. 

Find  the  same  for  Problem  88. 


97 
98 

99 
100 

lOI 

102 
103 
104 
105 


Fi 


89 
90 

91 
92 

93 

94 
95 


nd  the  I.  H.  P.  from  the  following  cards  and  data: 
Diameter    of    cylinder  =  36".     Scale    of    indicator    spring    30 
pounds  =  i" . 

Stroke  of  engine  =  3'. 
Revolutions  per  minute  =  40. 

Find  the  mean  effective  pressure  and  the  /.  H.  P.  for  each  stroke 
separately. 
6 


82 


MARINE    engines: 


1 06.  Find  the  number  of  pounds  of  water  necessary  to  be 
evaporated  per  hour  in  order  to  supply  the  engine  of  Problem  105 
with  steam  to  develop  the  power  calculated. 

107.  Find  the  ciJ-off  on  the  inboard  and  outboard  strokes  re- 
spectively, in  inches  from  the  beginning  of  the  stroke,  of  the 
engine  of  Problem  105. 


Fig.  33. 

108.  Determine  the  amount  of  condensation  or  rc-czvporation, 
if  there  be  any,  in  the  engine  of  Problem  105  during  the  inboard 
stroke,  supposing  that  the  steam  were  initially  dry  and  saturated. 

109.  Supposing  that  the  steam  contains  10  per  cent,  of  mois- 
ture when  it  is  received  in  the  cylinder;  find  the  number  of  pounds 
of  water  required  per  I.  H.  P.  per  hour  for  the  engine  of  Problem 
105. 

no.     Find  the  I.  H.  P.  from  the  followinji;  cards  and  data: 
Scale  of  indicator  spring  =:  20  pounds  to  the  inch. 
Diameter  of  the  cylinder  =  90". 
Stroke  of  the  engine  =:  40". 


Fiff.  34. 


PROBLEMS,  NOTES  AND  SKETCHES. 


83 


Revolutions  per  minute  are  sufficient  to  produce  a  mean  piston 
speed  of  800  feet  per  minute. 

111.  Find  the  water  required  per  I.  H.  P.  per  hour  in  the  en- 
gine of  Problem  no. 

112.  Find  the  number  of  pounds  of  water  that  must  be  evapo- 
rated per  hour  to  supply  the  engine  of  Problem  in  with  steam, 
supposing  that  the  steam  contains  initially  5  per  cent,  of  moisture. 

THE  MACOMB  STRAINER. 

Art.  28.— (P.  371,  S.  &  O.) 

It  is  necessary  to  fit  the  bilge  suction  pipes  of  all  pumps  with 
strainers  to  catch  anything  which  would  choke  the  pipes  and 
valves  of  the  pump  if  permitted  to  enter. 


Fig.  35. — Macomb  Strainer. 


The  Macomb  strainer,  shown  in  Fig.  35,  has  been  used  for  many 
years  in  the  ships  of  our  navy.  The  pump  suction  is  attached  to 
the  flange  L,  the  pipe  to  the  bilge  leads  from  the  flanged  nozzle  D. 
A  copper  basket  K  rests  on  an  interior  flange  in  the  chamber  and 
all  water  entering  the  pump  must  be  strained  through  the  holes  in 
this  basket. 

At  intervals  the  zving  nuts  are  unscrewed  and  the  cover  g  re- 
moved. The  basket  K  is  then  Hfted  out  by  the  handle  H  and  a 
spare  basket  put  in  place  of  K.  K  is  then  cleaned  ready  for  use 
to  replace  the  spare  basket  when  choked.  All  of  the  coarser  dirt 
is  thus  trapped  in  the  basket. 


84 


MARINE    engines: 


ASH  HOISTING  ENGINE. 
Art.  29  (P.  387,  S.  &  O.) 

I'ig-  36  is  one  form  of  the  "  Williamson  "  ash-hoist,  which  is 
used  in  our  navy.  It  consists  of  a  two-cylinder  engine,  with 
overhung  cranks,  driving  the  hoisting  drum;  each  engine  having 
a  single  eccentric  to  work  its  slide-valve. 

The  ash  buckets  are  raised  or  lowered  by  working  the  engine, 
by  means  of  the  hand  wheel  shown  on  the  left  of  the  figure,  which 
is  kept  moving  in  the  direction  it  is  desired  that  the  drum  revolve; 
thus  keeping  open  a  reversing  valve  (similar  to  the  one  shown 
in  Fig.  181  of  Sennett  &  Oram)  which  controls  the  supply  and 
direction  of  the  steam  for  the  two  engines.     When  the  movement 


WILIMMSON  BROS.  PATENT  RUTOMffTW flSH HOISTm  ENG/NE 


Fig.    36. 

of  the  hand  wheel  ceases,  a  further  small  movement  of  the  en- 
gines closes  the  reversing  valve  and  the  supply  of  steam  is  shut 
ofif  from  the  cylinders. 

Fig.  37  illustrates  this  valve  motion.  A  long  pinion,  cast  with 
sleeves  extending  on  either  side,  fitted  loose  on  the  "  automatic  " 
or  hand-wheel  shaft,  is  free  to  move  axially  on  the  shaft  for  a 
short  distance.  This  pinion  gears  into  a  spur  wheel  secured  to 
the  drum  shaft.  On  one  side  of  the  pinion  a  groove  is  cut  into 
the  sleeve,  and  in  this  groove  is  fitted  a  loose  collar  or  strap, 
which,  through  a  bell-crank,  moves  the  reversing  valve  when  the 
pinion  is  moved  either  to  the  right  or  left,  thus  reversing  the  flow 


3 

>i 

7 

A 

a 

> 

S 

'*j 

tH 

e 

^ 

85 


86  MARINE  engines: 

of  steam  through  the  pipes  leading  to  the  valve  chests  on  the 
cylinders.  At  each  end,  the  pinion  sleeve  has  a  spiral  face  cut 
on  it.  which  works  against  a  similar  spiral  cut  on  blocks  that  are 
secured  to  the  shaft;  so  that,  when  the  hand  wheel  and  its  shaft 
are  revolved  in  either  direction,  the  spiral  faces  force  the  pinion 
to  move  along  the  shaft,  so  opening  the  reversing  valve,  but  leaves 
it  still  in  gear  wath  the  spur  wheel  on  the  drum  shaft;  which,  on 
the  starting  of  the  engines,  tends  to  move  the  pinion  in  the  oppo- 
site direction  along  the  shaft,  so  bringing  it  back  to  the  central 
position  where  the  reversing  valve  is  closed. 

Therefore,  as  long  as  the  hand  wheel  is  turned,  the  engines  fol- 
low it;  but,  as  soon  as  the  motion  of  the  hand  wheel  ceases,  the 
pinion  will  catch  up  and  the  engine  stops. 

Safety  stops  are  put  on  to  prevent  the  pinion  being  moved  too 
far  along  the  automatic  shaft. 

The  screw  thread  shown  in  Fig.  36,  on  the  automatic  shaft, 
carries  a  nut  which  is  prevented  from  turning,  but  is  allowed  sufifi- 
cient  lateral  motion  between  stops  to  give  the  proper  amount  of 
hoist.  On  bringing  up  on  the  stops,  it  prevents  the  bucket  being 
raised  or  lowered  too  far,  and  thus  avoids  danger  of  breaking 
the  rope. 

STEAM  STEERIXG  EXGIXE. 

Art.  30  (P.  2^'j2,  S.  &  O.). — Fig.  38  shows  a  steering  engine  as 
applied  to  one  of  our  large  cruisers  or  battle-ships,  which  has  the 
same  valve  motion  as  the  ash-hoist  described  in  the  preceding 
article.  The  automatic  shaft  is  shown  at  L  in  the  plan:  A''  shows 
one  of  the  steam  cylinders  and  a  pointer  below  that  letter  shows 
a  rudder  tell-tale,  which  is  used  wdien  the  steering  engine  is  tried 
or  worked  by  means  of  the  hand  wheel  /;  H  is  the  steering  en- 
gine crank  shaft  (the  letter  H  being  placed  below  the  shaft  on  the 
plan  and  above  it  on  the  elevation);  which  carries  a  spur  wheel 
that  gears  into  the  large  spur  wheel  (w'hich  also  carries  the  small 
spur  wheel  abaft  it  that  gears  into  the  pinion  on  the  automatic 
shaft  L)  fitted  loose  on  the  shaft  G,  but  to  which  it  can  be  secured 
by  the  clutch  M.  The  shaft  G  extends  from  the  wheels  P  to  the 
bearing  just  forward  of  the  rudder  head;  the  after  part  of  G  is 
threaded  with  a  right  and  left  hand  screw  thread  on  w'hich  work 
driving  nuts,  kept  in  line  by  side  rod  guides.     The  driving  nuts 


IWI 


WILLIAMSON-BROS.-PATENT-STEERINDCEAR. 

AS-APPLIEO-Ta-THE 

MODERNBATTLE-  SHIPS 

OF-THE 

UNITEDSTATESNAVY. 


PROBLEMS,  NOTES  AND  SKETCHES.  8/ 

move  in  opposite  directions  and  are  each  connected  to  its  end  of 
the  yoke  on  the  rudder  head  by  means  of  connecting  rods. 

The  vessel  can  be  steered  by  steam:  first,  by  means  of  the 
hvdrauhc  tclcmotor  K,  which  works  the  shaft  L  through  bell- 
cranks;  second,  by  means  of  motion  given  to  the  drum  /  through 
a  rope  leading  from  the  steering  wheel  in  the  conning  tower,  on 
the  bridge  or  other  deck  station,  which  motion  is  conveyed  to  L 
by  the  bevel  gears  shown  in  the  plan;  third,  by  motion  received 
through  the  shaft  0,  which  is  connected  by  shafting  and  gearing 
to  a  wheel  on  deck,  and  which  can  be  connected  to  L,  through 
the  smaller  vertical  shaft  and  the  gearing  shown  in  elevation  over 
the  letters  /  and  K;  fourtli,  through  the  wheel  /,  wdiich  is  also  used 
for  trying  the  engine  before  getting  underway. 

The  vessel  can  be  steered  by  hand  power:  first,  by  means  of 
the  shaft  0,  which  can  be  geared  to  G  through  the  larger  vertical 
shaft  shown  in  the  elevation;  second,  tlirough  the  wheels  P,  lo- 
cated in  the  steering  engine  room,  which  can  be  thrown  into  gear 
by  means  of  the  coupling  shown  on  the  forward  end  of  G.  In 
either  of  the  above  methods  of  steering  by  hand  power,  the  clutch 
Kl  must  be  thrown  out  of  gear,  so  that  G  can  revolve  without 
moving  the  spur  wheels  and  engines,  or  giving  motion  to  L. 

To  use  one  of  the  above  methods  of  steering,  either  by  steam 
or  hand  power,  its  particular  clutch  must  be  put  in  gear,  and  the 
clutches  for  the  other  five  methods  thrown  out  of  gear. 

Also,  a  long  tiller  is  fitted  above  the  yoke  on  the  rudder  head, 
to  the  forward  end  of  which  side  tackles  can  be  hooked,  and  the 
vessel  steered  by  this  means.  If'the  vessel  is  steered  by  the  tiller, 
the  connecting  rods  must  be  disconnected  from  the  yoke  on  the 
rudder  head. 

There  is  a  working  model  of  a  Williamson  steering  engine  in 
the  Department  of  Seamanship. 

DISTILLING  APPARATUS  IN  THE  U.  S.NAVY. 

Art.  31  (P.  400,  S.  &  O.). — On  U,  S.  vessels  the  term  condenser 
is  applied  to  the  apparatus  used  to  condense  the  exhaust  steam 
from  the  engines,  while  the  apparatus  used  for  making  potable 
fresh  water  is  usually  called  a  distiller. 

Fig.  39  shows  the  type  of  distiller  fitted  on  the  latest  of  our 
naval  vessels.  The  shell  is  of  cast  iron  and  the  tube  sheets  of 
composition.     Where  it  is  possible  the  shell  stands  upright,  the 


t 


Fie:.  39. 


C<"it!<'**'3  "'*'*'■  *"'**' 


Uf'<s<x>»  if^C 


•cJalmy  -/.^«-  .iJ^.». 


Jty/^.^.V:^.^^!.:,.',^  ,.fy^.  JJIJJiT^ 


a 


ann 


cms 

ODS 


QGS 


^2D 
^2D 


Fig.  40. — Baird's  Distiller. 
89 


90 


MARINE    engines: 


end  A  being  on  top.  If  placed  horizontally,  the  side  C  is  on  top. 
The  tubes  are  ordinarj-  condenser  tubes,  Y^"  outside  diameter. 
No.  1 6  wire  gauge.  They  are  expanded  into  the  tube  sheets, 
the  lower  tube  sheet  being  arranged  to  slide  in  a  stuffing  box  to 
allow  for  the  expansion  of  the  tubes. 

The  condensing  water  enters  at  B  and  flows  out  at  A.  Steam 
from  the  evaporator  enters  at  C  and  the  condensed  fresh  water 
is  drawn  off  at  D.  The  perforated  diaphragm  under  C  is  for  the 
purpose  of  distributing  the  entering  steam  over  a  wider  area  and 
thus  preventing  injury  to  the  tubes  at  the  entrance. 

Fig.  40  shows  a  type  of  Baird's  distiller,  which  is  on  many  of 
uur  older  vessels.  It  consists  of  a  copper  or  composition  shell 
in  which  are  coiled  tinned  copper  tubes,  each  of  which  passes  at 
top  and  bottom  into  the  chambers  where  valves,  arranged  as 
shown,  enable  each  coil  to  be  shut  off  independently  of  the  oth- 
ers. This  feature  is  useful  in  case  of  a  leaky  coil,  enabling  the 
defective  coil  to  be  located  and  shut  off,  the  others  still  remain- 
ing in  use. 

There  are  brass  nipples  brazed  into  the  elbows  at  the  ends  of 
each  coil  which  pass  through  the  tube  plates  and  are  secured  by 
nuts.  The  joints  between  the  salt  and  fresh  water  sides  of  the 
tube  plates  being  made  tight  by  the  nuts  being  recessed  at  the 
bottom  and  screwed  down  on  Avicking. 

Fig.  41  shows  the  type  of  evaporator  fitted  on  most  of  our 
naval  vessels.  It  has  a  cylindrical  shell  similar  to  a  boiler  shell. 
The  arrangement  of  tubes  and  steam  and  water  connections  are 
clearly  shown. 

Steam  gauges,  water  glasses,  bottom  blow,  safety  valve,  and 
other  fittings,  as  used  on  a  boiler,  are  fitted;  the  evaporator  being 
in  reality  a  boiler  whose  evaporating  agent  is  steam  instead  of 
fire. 

This  type  of  evaporator  is  made  in  various  sizes  to  suit  differ- 
ent vessels,  the  larger  vessels  being  usually  supplied  with  two, 
each  having  about  5000  gallons  capacity  per  day. 

Owing  to  its  high  evaporative  power,  an  evaporator  will  prime 
unless  very  carefully  handled.  The  presence  of  a  small  quantity 
of  salt  will  make  the  water  bad  for  drinking  purposes,  so  it  is 
necessary  to  avoid  this.  Care  must  be  taken  not  to  carry  the 
water  level  too  high,  the  best  results  being  obtained  when  it  is 
just  below  the  upper  row  of  tubes.     If  carried  lower  there  will  be 


91 


92  MARINE    engines: 

no  injurious  results  and  the  uncovered  tubes  will  tend  to  super- 
heat the  steam  and  reduce  priming.  From  twelve  to  fifteen 
pounds  pressure  is  usually  carried  on  the  shell  when  making 
water  for  drinking  purposes.  The  stop  valve  on  nozzle  to  distil- 
ler is  regulated  to  obtain  the  maximum  output  without  priming, 
and  the  stop  valve  admitting  boiler  steam  to  the  tubes  is  regu- 
lated to  keep  up  the  pressure  in  the  tubes  to  about  thirty-five 
pounds. 

\\  hen  the  distillers  are  on  a  level  considerably  above  the  evapo- 
rators, and  the  connecting  pipe  has  no  downward  bends  the 
water  drains  back  to  the  evaporators  and  the  efifect  of  priming 
is  much  reduced.  On  the  U.  S.  S.  Xew  York  the  evapora- 
tors and  distillers  are  on  the  same  level.  After  considerable 
trouble  from  priming,  the  pipe  from  evaporators  was  carried 
well  up  the  hatch;  then,  with  a  reverse  bend,  back  to  the  distil- 
lers, the  pipe  being  well  covered  with  non-conducting  material. 
It  was  then  found  possible  to  keep  the  stop  valve  wide  open  with- 
out salt  water  being  carried  over,  and  the  output  was  much  in- 
creased. 

When  operating  in  connection  with  a  condenser,  for  making 
water  for  the  boilers,  the  evaporator  is  under  a  partial  vacuum  and 
the  product  is  much  larger  than  when  using  with  a  distiller.  The 
water  produced  may  be  slightly  brackish,  but  the  lime  salts,  which 
make  boiler  scale,  are  left  behind  in  the  evaporator,  and  the  com- 
mon salt  (sodium  chloride)  which  is  carried  over  has  no  injurious 
effect  on  the  boilers. 

A  salinometeV  pot  is  fitted  to  the  evaporator  for  taking  the 
saturation.  The  evaporator  should  not  be  blown  down  until  the 
saturation  is  4-32nds. 

To  scale  the  evaporator  tubes,  which  should  be  done  when  a 
scale  of  %"  or  more  in  thickness  has  formed,  the  pipes  in  front 
are  cleared  away,  the  joint  on  evaporator  head  is  broken,  and 
the  nest  of  tubes  taken  out.  They  are  then  thoroughly  scaled  and 
cleaned  before  replacing.  Sometimes,  a  spare  nest  of  tubes  is 
carried,  which  can  be  put  in  when  the  evaporator  is  opened,  and 
but  little  time  is  then  lost;  the  nest  taken  out  being  scaled  at  leis- 
ure. 

MULTIPLE  EFFECT  EVAPORATIXG  PLANTS. 

Art.  32. — Large  evaporating  plants  are  fitted  with  only  the  first 
evaporator,  in  a  set  of  three,  using  steam  from  the  boiler.     The 


PROBLEMS,  NOTES  AND  SKETCHES.  93 

steam  produced  passes  to  the  tubes  of  a  second  evaporator,  and 
the  steam  produced  in  the  second  to  the  tubes  of  a  third.  The 
tliird  evaporator  is  connected  with  a  condenser  and  works  under 
a  vacuum. 

It  is  said  that  an  efficient  plant  of  this  kind  will  produce  twenty 
pounds  of  fresh  water  per  pound  of  coal,  which  is  about  two  and 
a  half  times  the  evaporative  power  of  a  fairly  efficient  boiler.  The 
U.  S.  Ships  Rainkw  and  Iris  have  been  fitted  out  as  dis- 
tilling ships.  Each  has  twelve  evaporators  of  large  size,  arranged 
to  work  in  either  single,  double,  or  triple  effect.  Xo  figures  have 
been  published  giving  data  as  to  their  performance. 

MANAGEMENT  OF  BOILERS  AND  ENGINES  ON 
BOARD  SHIP. 

(Chap.  XXIX.,  S.  &  O.) 

Work  Preliminary  to  Starting  Fires. 

Art.  33. — The  normal  condition  of  the  ship  may  be  taken  as  at 
anchor  with  steam  on  one  boiler  and  the  auxiliary  steam  pipe; 
the  other  boilers  closed  and  filled  completely  or  else  to  steaming 
level  with  fresh  water. 

The  order  to  get  up  steam  should  be  given  six  or  eight  hours 
— according  to  the  size  of  boilers — before  the  time  set  for  getting 
underway  unless  the  boilers  are  provided  with  circulating  appa- 
ratus, in  which  case  half  that  time  will  be  sufficient.  The  order 
should  also  state  the  speed  required. 

Select  a  number  of  boilers  judged  to  be  sufficient,  taking  those 
that  have  been  used  least,  arranging,  if  possible,  to  have  all  in 
the  same  fireroom  and  as  far  as  possible  from  any  boiler  that  may 
be  out  of  repair  or  that  may  require  cleaning  while  underway — 
also  they  should  not  be  far  from  the  coal  supply.  Remember  that 
the  steam  pressure  will  be  most  easily  controlled  and  economy 
of  coal  ensured,  if  there  are  enough  boilers  to  furnish  steam  with 
moderately  heavy  fires  and  moderate  draught,  and  also  if  the  run 
is  to  be  more  than  24  hours  long,  the  fires  will  have  to  be  cleaned. 
If  the  vessel  is  to  manoeuvre  with  a  fleet,  enough  fires  should  be 
lighted  to  furnish  steam  for  a  speed  two  knots  greater  than  that 
named  in  the  order  setting  the  speed  for  the  fleet.  If  heavy 
guns  are  to  be  used  for  target  practice  it  is  advisable  not  to  have 


94  MARINE  engines: 

any  boiler  empty  for  repairs,  etc.,  but  fill  every  one  not  in  use, 
to  check  vibrations  which  would  be  liable  to  start  leaks. 

If  the  boilers  to  be  used  are  perfectly  full,  pump  out  or  drain 
down  the  water  to  middle  of  gauge  glass.  See  that  the  cocks  on 
pipes  leading  to  steam  gauge  and  top  and  bottom  of  water  gauge 
are  open,  the  air  cocks  and  drain  cocks  shut.  The  drain  may 
be  open  yet  choked  up  sufficiently  to  allow  the  boiler  to  hold 
water.  When  a  pressure  comes  on  it  will  blow  through  and  be 
difficult  to  close.  If  the  drain  cock  has  a  handle  take  it  off  to 
prevent  its  being  accidentally  opened.  As  a  check  on  the  water 
gauge,  try  the  salinometer  pot  and  see  if  water  flows  out;  also 
tap  on  front  of  boiler  with  a  hammer  and  judge  the  height  of 
water  by  the  sound.  Start  the  main  boiler  stop  valve  ofi.  its  seat 
and  open  the  test  cocks.  On  ships  like  the  Charleston,  which 
have  no  auxiliary  steam  pipe  system,  it  will  be  necessary  to  keep 
the  boiler  stop  valves  shut  until  the  pressure  rises  up  to  that  of 
the  auxiliary  boiler.  In  this  case  the  hot  air  must  be  allowed  to 
escape  by  raising  the  safety  valves  and  keeping  them  open  until 
steam  forms.  Otherwise  the  safety  valves  should  be  kept  closed. 
Remove  smoke-pipe  cover,  slack  smoke-pipe  guys,  light  gauge 
and  other  lamps  if  there  are  no  electric  lights.  Close  furnace 
and  ash  pit  doors  of  all  boilers  not  in  use  and  see  their  main 
stop  and  check  valves  closed.  While  this  has  been  going  on  the 
coal  passers  should  have  gotten  out  and  placed  in  front  of  each 
furnace  several  buckets  of  coal  containing  a  good  proportion  of 
lumps.  If  the  lumps  are  larger  than  a  man's  fist  they  should  be 
broken  with  a  coal  maul  having  a  rather  sharp  point  so  that  the 
lumps  will  be  broken  into  pieces  rather  than  be  pounded  to  fine 
dust.  If  the  coal  is  all  dust  it  should  be  sprinkled  with  water  to 
keep  it  from  falling  through  the  bars. 

The  grate  is  now  to  be  covered  with  a  layer  of  coal  from  three 
to  six  inches  thick,  extending  to  within  about  one  foot  of  the  door. 
The  thickness  will  depend  upon  whether  the  coal  is  fine  or 
lumpy.  If  the  layer  is  too  thin  air  will  pass  and  spoil  the  draught. 
If  too  thick  it  will  take  a  long  time  to  get  thoroughly  ignited  and 
then  the  fires  will  be  too  heavy  and  hard  to  manage. 

Starting  Fires. 

On  some  ships  it  is  customary  to  notify  the  officer  of  the  deck 
through  the  engine-room  speaking  tube  just  before  starting  fires; 


PROBLEMS,  NOTES  AND  SKETCHES.  95 

on  Other  ships  he  is  notified  after  all  fires  are  started.  All  fur- 
naces in  one  boiler  should  be  started  at  the  same  time  to  avoid 
unequal  expansion  of  diiTerent  parts. 

If  bituminous  coal  is  used  the  fires  may  be  started  by  using 
shovelfuls  of  live  coals  from  the  auxiliary  boiler.  If  anthracite 
is  used  it  will  be  necessar\^  to  lay  a  double  handful  of  oily  waste 
or  shavings  on  the  front  of  the  grate;  cover  this  with  an  armful 
of  kindling  wood  and  the  wood  with  lumps  of  coal. 

The  amount  of  wood  will  depend  upon  the  time  available  for 
getting  the  fires  started. 

If  there  is  a  water  circulating  apparatus  it  is  started  at  the  same 
time  as  the  fires  and  continued  until  steam  has  formed.  On  ships 
fitted  with  Weir's  Hydrokineter  it  is  usually  customary  to  start 
them  twelve  to  sixteen  hours  before  lighting  fires  and  have  the 
water  heated  nearly  to  boiling  point.  Instead  of  keeping  fires 
banked  the  water  may  be  kept  hot  in  this  way  with  steam  from 
another  boiler,  and  full  pressure  raised  in  two  or  three  hours 
after  lighting  fires. 

While  the  fires  are  burning  up,  the  furnace  doors  are  left  ajar 
and  ash-pit  doors  partly  closed.  As  the  coal  becomes  ignited  at 
the  front  it  is  worked  back  from  time  to  time  with  the  hoe  and 
mixed  with  the  coal  at  the  back  and  fresh  fuel  is  put  on  in  front. 

The  coal  passers  now  begin  to  get  out  rounds  of  coal  at  regular 
intervals  until  the  end  of  the  run. 

About  this  time  a  deep  rumbling  sound  accompanied  by  a 
strong  vibration  of  the  boiler  is  sometimes  heard.  It  is  due  to 
strong  draught  and  indicates  that  there  are  holes  in  the  fire.  If 
no  holes  are  found,  check  the  draught  by  partly  closing  the  dam- 
pers. 

The  fact  that  all  the  coal  on  the  grate  is  ignited  is  known  by  a 
bright  clear  glow  throughout  the  ash-pit.  It  is  now  time  to  close 
furnace  doors  entirely  and  open  ash-pit  doors  wide. 

The  fires  must  be  kept  levelled  ofT,  sprinkled  with  fresh  coal 
from  time  to  time,  and  kept  shoved  back  from  the  furnace  doors 
to  avoid  burning  the  inner  linings.  The  ash-pits  must  be  kept 
free  from  coal  that  falls  through  the  grates  without  being  burnt, 
also  live  coals,  both  of  which  are  liable  to  overheat  the  bars.  A 
thin  layer  of  ashes  however  may  be  left  to  protect  the  metal. 
Avoid  heaping  up  fire  at  the  back  of  the  grate,  thereby  checking 
the  draught. 


96  MARINE    engines: 

Since  differences  in  draught,  coaling,  firing,  etc.,  will  cause 
steam  to  form  at  widely  dififerent  times  in  different  boilers  and 
may  cause  it  to  form  too  soon  or  too  late,  the  temperature  of  the 
water  in  the  boilers  should  be  taken  every  half  hour  after  fires 
are  started  and  the  fires  urged  or  checked  so  that  the  rise  of  tem- 
perature each  half  hour  shall  be  the  same.  It  should  never  ex- 
ceed 36°  F.  per  half  hour.  If  the  draught  is  abnormally  poor  the 
blowers  may  be  used,  taking  care  not  to  exceed  ^-inch  water 
pressure.  The  formation  of  steam  will  be  shown  by  escape  of 
vapor  from  the  test  cocks,  which  are  then  to  be  shut  and  all  hot 
air  and  steam  allowed  to  pass  through  main  steam  pipe  and  into 
main  engines,  taking  care  to  open  all  drains  on  these  pipes,  on 
valve  chests,  etc.  (If  as  in  the  case  before  mentioned  there  is 
no  auxiliary  steam  pipe,  the  safety  valves  are  closed  as  soon  as 
all  air  is  judged  to  have  escaped  and  the  pressure  in  each  boiler 
allowed  to  rise  to  the  maximum,  connecting  each  boiler  up  in 
turn  to  the  main  steam  pipe  when  its  pressure  is  equal  to  or  a 
little  above  that  already  in  the  pipe.)  As  the  pressure  rises  to  8 
or  10  pounds  it  will  be  necessary  to  close  all  drains  which  are 
blowing  steam,  drain  steam  drums  and  separator  or  main  steam 
pipe  and  open  boiler  stop  valves  full  (two  or  three  turns  if  globe 
valves).  The  smoke-pipe  guys  previously  slackened  must  now 
be  set  up  moderately  taut.  It  will  take  an  hour,  more  or  less, 
for  steam  to  attain  its  full  height,  the  time  depending  upon  a 
great  variety  of  circumstances  and  conditions.  As  it  rises  keep 
a  good  lookout  about  the  boiler  and  pipes  for  leaks  of  water  and 
steam.  If  anything  serious  develops  it  will  be  necessary  to  start 
fires  in  another  boiler  at  once. 

Control  of  Steam. 

The  management  of  the  steam  will  require  the  greatest  skill 
and  care  as  the  pressure  reaches  the  limit  and  the  fires  have  be- 
come thoroughly  ignited.  Opening  furnace  doors  and  pump- 
ing cool  water  into  the  boilers  to  keep  down  steam  pressure  is 
strictly  prohibited.  These  methods  must  be  resorted  to  only 
when  everything  else  fails.  It  is  also  inadvisable  to  open  con- 
nection doors.  The  first  thing  to  do  is  to  shut  dampers  and 
partly  close  ash-pit  doors.  If  these  do  not  answer,  open  the 
bleeders.  On  all  modern  war  vessels  the  bleeders  are  purposely 
made  large  enough  to  give  good  control  of  the  steam.     Care 


PROBLEMS,  NOTES  AND  SKETCHES.  97 

should  be  taken  however  not  to  open  the  bleeders  suddenly,  as 
by  doing  so  there  is  danger  of  cracking  the  condenser  tubes.  If 
the  bleeder  is  not  sufBcient.  raise  the  safety  valves.  On  our  most 
recent  naval  vessels  the  safety  valves  are  connected  with  the  dr}- 
pipes  so  that  there  is  not  the  danger  of  lifting  water  out  of  the 
boilers  which  used  to  cause  such  dread  of  raising  safety  valves. 
A  good  practical  and  economical  expedient  for  controlling  the 
steam  is  to  see  that  the  evaporator  is  not  in  use  while  steam 
is  forming.  Then  start  it  and  stop  it  as  occasion  requires  to 
use  surplus.  All  the  ventilating  blowers  may  be  started  and 
stopped  for  the  same  purpose  if  the  evaporator  is  not  sufficient, 
also  bilge  and  fire  pumps.  A  large  amount  of  surplus  steam 
may  be  worked  off  to  advantage  by  having  the  main  engines 
ready  to  tr}-  just  about  the  time  steam  reaches  the  limit — but  this 
is  not  always  convenient  or  practicable.  When  steam  is  up  to 
the  limit  and  the  fires  are  burning  well,  report  to  engine  room, 
"  ready  to  get  underway."  Be  sure  about  the  fires  before  making 
this  report.  A  poor  fire  will  expand  a  quantity  of  steam  bottled 
up  in  the  boiler  until  the  pressure  rises  to  the  limit.  A  few 
strokes  of  the  engine  may  carry  off  all  this  pressure  and  then  the 
water  may  go. 

Standing  By. 

After  all  is  ready  in  the  fire  room,  it  often  happens  that  the 
time  for  getting  underway  is  postponed.  If  the  delay  is  to  be 
for  only  two  or  three  hours,  the  fires  may  be  left  spread  and 
lightly  coaled  from  time  to  time,  keeping  the  evaporator  work- 
ing to  full  capacity,  the  ventilating  blowers  all  going  and  if  found 
necessary  by  experience,  keep  the  bleeders  partly  open.  If  some 
such  precautions  are  not  taken,  at  the  end  of  the  time  set,  the 
efforts  to  keep  steam  down  will  have  so  deadened  the  fires  that 
after  the  main  engines  have  run  a  short  time  the  steam  wuU  fall 
rapidly,  thereby  incurring  the  risk  of  the  ship  becoming  unman- 
ageable while  going  out  of  port  or  not  being  able  to  keep  place 
in  line  or  to  execute  the  necessary  manceuvres  with  the  fleet. 

Banking  Fires. 

For  a  delay  of  three  to  six  hours,  the  fires  may  be  banked,  first 
allowing  them  to  burn  down  a  little,  cleaning  them  if  necessary, 
then  shoving  them  towards  the  back  of  the  grate  in  a  heap.     If 


98  MARINE    engines: 

banked  when  too  heavy  the  necessary  stirring  up  may  cause  the 
pressure  to  rise  so  fast  that  it  will  be  hard  to  control  without 
waste.  Fires  should  not  be  banked  at  the  front  of  the  furnace, 
as  in  that  case  cold  air  will  pass  through  the  grates  at  the  back 
and  strike  the  back  tube  sheets,  the  most  sensitive  part  of  the 
boiler.  When  fires  are  banked  the  dampers  should  be  closed 
and  ash-pit  doors  partly  so,  otherwise  a  large  amount  of  coal 
may  be  wasted  heating  up  the  air  which  sweeps  over  the  fires.  If 
dampers  are  too  tight  and  the  coal  contains  much  gaseous  matter, 
explosive  gases  may  form  and  explode  in  the  combustion  cham- 
bers. If  ash-pit  doors  are  shut  too  tight  there  is  danger  of  over- 
heating and  melting  the  grate  bars.  Lying  under  banked  fires  is 
liable  to  cause  leaks  about  the  boiler  seams  and  tubes.  There  is 
a  variety  of  opinion  with  regard  to  the  exact  causes  but  no  ques- 
tion about  the  fact.  If  the  delay  is  to  exceed  five  or  six  hours 
it  is  better  not  to  bank  fires  but  to  let  them  burn  down  slowly 
and  when  they  have  completely  died  out,  haul  them  quickly  and 
immediately,  close  the  furnace  and  ash-pit  doors  and  dampers. 
A  long  series  of  experiments  tried  on  German  naval  vessels  shows 
that  to  lie  under  banked  fires  for  twenty-four  hours  requires  as 
much  coal  as  would  be  necessan*^  to  start  all  the  fires  afresh.  The 
exact  amount  should  be  learned  by  experiment  for  each  vessel 
and  a  record  kept  for  reference. 

On  naval  vessels,  however,  it  is  sometimes  necessary  for  mili- 
tary- purposes  to  lie  under  banked  fires  in  order  to  be  ready  to 
get  underway  at  short  notice  at  some  unknown  future  time,  and 
considerations  of  economy  of  coal  and  injury  to  boilers  must  be 
disregarded.  When  fires  have  been  banked  for  about  12  hours 
a  systemati-c  cleaning  of  them  must  be  begun,  taking  one-third 
the  whole  number  each  watch. 

When  under  banked  fires  and  the  order  is  received  to  get 
underway,  if  there  is  plenty  of  coal  on  the  floor  plates,  it  will  take 
about  ten  or  fifteen  minutes  to  get  all  the  fires  spread  and  fifteen 
to  thirty  minutes  more,  under  ordinary  conditions,  for  the  fires 
to  burn  up  before  it  will  be  safe  to  attempt  to  get  up  anchor. 

Management  of  Fires  Underway. 

The  aim  is  to  keep  a  uniform  pressure  of  steam  regardless  of 
the  varying  speed  of  the  engine  and  at  the  same  time  to  econo- 
mize coal.     As   the   boilers   are   in   separate   compartments   and 


PROBLEMS,  NOTES  AND  SKETCHES.  99 

often  the  main  engines  can  neither  be  seen  nor  heard  it  is  advis- 
able to  provide  some  speed  indicator  or  simple  apparatus  by 
means  of  which  the  water  tender  will  be  kept  informed  of  every 
change  and  that  he  may  know  at  once  if  fluctuations  of  steam  are 
due  to  variations  of  speed.  He  should  also  be  informed  in  ad- 
vance, when  possible,  of  proposed  changes. 

Firing  a  Furnace. 

A  furnace  should  be  fired  when  the  layer  of  coal  has  burned 
down  to  three-fourths  its  normal  thickness.  First  close  the  dam- 
per, level  the  fire,  throw  a  few  shovelfuls  of  coal  on  the  front 
of  the  grate  to  check  radiation,  then  begin  at  the  back  spreading 
the  coal  evenly  all  over  and  work  towards  the  front.  Push  the 
coal  away  from  the  furnace  door,  work  quickly  and  get  the  doors 
shut  as  quickly  as  possible,  then  open  the  damper.  Then  clear 
the  spaces  between  the  bars  with  the  "  pricker  bar."  and  haul  the 
ash-pans.  Any  good  live  coals  that  may  have  fallen  through  the 
bars  may  now  be  separated  from  the  ashes  and  returned  to  the 
furnace.  The  fires  should  be  carried  about  5  inches  thick  for 
anthracite  coal  and  moderate  draught,  increasing  the  thickness 
for  stronger  draught  and  bituminous  coal  to  10  or  12  inches. 

The  furnaces  must  be  fired  in  rotation,  each  succeeding  fur- 
nace being  chosen  as  far  as  possible  from  the  preceding  one.  If 
a  fire  is  in  good  condition,  as  soon  as  the  fresh  coal  has  ignited 
a  bright  clear  light  will  be  seen  in  the  ash-pit.  If  after  this  the 
ash-pit  looks  dull,  the  spaces  between  the  grate  bars  must  be 
thoroughly  cleaned  with  a  pricker  bark.  If  this  cannot  be  done 
owing  to  slag  sticking  to  bars,  use  a  slice  bar  to  detach  it  and 
rake  to  haul  it  out. 

Cleaning  Fires. 

If  there  is  much  slag  or  clinker  on  the  bars  it  will  be  neces- 
sary to  give  the  fires  a  thorough  cleaning.  As  a  rule  fires  will 
do  without  cleaning  for  about  twenty-four  hours,  so  that  on  runs 
not  exceeding  a  day  no  thorough  cleaning  will  be  required.  If 
there  is  any  chance  of  the  run  being  longer,  the  cleaning  should 
begin  about  12  hours  after  the  fires  are  started,  one-third  of  the 
fires  being  taken  each  watch. 

The  front  connection  doors  are  chalked  i,  2  and  3,  to  show 
which  furnaces  are  to  be  cleaned  by  the  respective  watches.     The 


lOO  MARINE    engines: 

fires  to  be  cleaned  by  any  one  watch  should  be  selected  as  far 
apart  as  possible.  Before  beginning  report  the  necessity  to  the 
engine  room.  First  allow  the  fire  to  burn  down  as  thin  as  pos- 
sible without  allowing  air  to  get  through,  taking  care  to  keep  it 
levelled  ofi  and  allowing  no  holes.  An  expert  water  tender  will 
also,  at  the  same  time,  gradually  increase  the  water  level  in  the 
boiler  so  that  while  cleaning  fires  and  afterwards  while  fires  are 
burning  up,  he  may  shut  ofif  the  feed  as  well  as  the  blow  entirely 
and  thus  secure  a  more  uniform  development  of  steam. 

In  the  meantime  get  the  necessar}^  tools  ready,  the  ash  hose 
led  out,  and  remove  all  coal  from  before  the  furnaces.  Begin 
by  closing  the  damper,  then  with  the  hoe  shove  back  all  the  good 
fire,  leaving  the  slag  and  clinker  exposed ;  dislodge  the  latter  with 
slice  bar,  and  remove  it  with  the  rake,  whereupon  it  is  imme- 
diately wet  down  by  a  coal  passer.  Now  haul  the  good  fire  for- 
ward leaving  the  slag  and  clinker  at  the  back  bare.  Remove  it 
as  before.  Finally  spread  the  good  fire  evenly  over  the  whole 
surface  of  the  grate.  If  the  amount  left  is  not  sufficient  a  few 
shovelfuls  may  be  taken  from  the  furnace  of  another  boiler.  Then 
sprinkle  the  whole  with  fresh  coal,  open  the  damper,  and  haul 
ash-pans. 

Instead  of  shoving  the  good  fire  back  it  may  be  pushed  first  to 
one  side  then  to  the  other.  When  wetting  down  ashes  be  careful 
to  not  get  any  water  on  the  front  of  boiler  or  furnaces.  Tlie 
operation  should  be  completed  in  from  8  to  lo  minutes  accord- 
ing to  the  amount  of  clinker  and  to  the  way  in  which  it  sticks  to 
the  bars.  When  working  full  speed  with  forced  draught  the 
operation  of  cleaning  fires  often  consists  in  hauling  out  of  the  fur- 
nace everything  good  or  bad  and  starting  a  new  fire.  It  takes 
about  four  minutes. 

After  cleaning  a  fire  time  should  be  given  for  it  to  get  into 
good  condition  before  beginning  to  clean  another  fire. 

Sweeping  Tubes. 

After  steaming  several  days  with  bituminous  coal  and  indiffer- 
ent draught,  the  tubes  will  begin  to  choke  up;  this  will  be  indi- 
cated by  a  fall  in  the  steam  pressure  if  the  draught  is  poor,  but 
if  the  draught  is  good,  ashes  and  cinders  will  be  thrown  out  of 
the  smoke-pipe.  The  exact  condition  of  affairs  is  ascertained 
by  opening  the  connection  doors.     If  the  tubes  require  cleaning 


PROBLEMS,  XOTES  AND  SKETCHES.  lOI 

it  may  best  be  done  by  using  a  steam  jet  and  flexible  hose  often 
provided  for  the  purpose,  first  closing  ash-pit  doors  to  check 
the  draught.  Before  beginning  allow  the  fires  to  burn  down 
somewhat  and  ascertain  if  there  are  any  wash  clothes  or  clean 
hammocks  on  the  line.  If  so  inform  the  officer  of  the  deck 
through  the  engine  room  of  the  necessity  of  sweeping  the  tubes, 
in  order  that  he  may  have  the  wash-clothes,  etc.,  piped  down. 
Sweeping  with  steel  or  coir  brushes  is  more  tedious.  In  any  case 
do  not  take  time  to  clear  tubes  that  may  be  choked  with  salt  so 
that  the  brushes  do  not  easily  pass  through.  Begin  with  the  top 
row  of  tubes  and  when  finished  sweep  out  the  front  connections 
before  closing  the  doors. 

As  sweeping  the  tubes  checks  the  formation  of  steam  only  one 
nest  should  be  swept  at  a  time  and  while  this  is  going  on  fires 
must  be  urged  in  the  other  boilers.  The  feed  may  also  be  shut 
down  for  a  time. 

Routine  of  the  Watch  at  Sea. 

The  routine  is  about  as  follows:  begin  cleaning  fires  about  15 
or  20  minutes  after  the  watch  conies  on  and  continue  at  intervals 
until  all  the  fires  assigned  to  the  watch  are  cleaned,  which  will 
be  about  six  bells.  After  each  fire  is  cleaned  it  must  be  allowed 
to  burn  up  and  get  into  condition  for  making  steam.  After  this 
it  is  useless  to  wait  any  longer  before  beginning  to  clean  the  next 
fire.  Naturally  the  intervals  of  time  between  cleaning  of  dififerent 
fires  will  vary  according  to  the  amount  of  fresh  coal  required  to 
get  the  fire  up  to  its  original  thickness.  As  soon  as  the  fires  are 
all  cleaned,  the  ashes  wet  down  and  heaped  near  the  ash-hoist, 
report  to  the  officer  of  the  deck  through  the  engine  room  that 
ashes  are  ready  for  hoisting.  Several  deck  hands  will  then  be 
detailed  to  carry  the  buckets  from  the  as^h-hoist  on  deck  to  the 
ship's  side  and  dump  them.  A  fireman  is  in  the  meantime  de- 
tailed to  get  the  ash  engine  ready  and  the  coal  passers  stand  by 
to  fill  ash  buckets.  The  fire  room  is  to  be  swept  clean  as  the  last 
buckets  go  up  and  a  round  of  coal  for  the  next  watch  is  laid  out 
in  front  of  all  furnaces  except  the  one  that  is  to  be  cleaned  first 
by  the  next  watch.  That  fire  is  to  be  allowed  to  burn  down  and 
the  water  level  in  the  boiler  is  gradually  raised  a  little  above  the 
normal  height.  During  the  whole  watch  a  steady  feed,  both  with 
regard  to  quantity  and  temperature,  is  to  be  kept  on  all  boilers 


I02  MARINE    engines: 

except  in  cases  mentioned,  where  for  special  reasons  the  water 
level  is  raised  or  lowered.  The  fact  of  the  check  valves  working 
is  ascertained  by  putting  the  ear  to  the  valve  chamber.  The  feed 
pipe  inside  of  check  away  from  the  boiler  should  not  be  hotter 
than  the  feed  water.  If  the  amount  of  water  in  the  gauge  is 
greater  than  it  should  be  judging  from  the  normal  feed  and 
known  opening  of  the  check,  the  cause  should  be  inquired  into 
at  once.  When  the  boilers  are  placed  in  an  athwartship  direction 
and  the  ship  has  a  list  to  port,  the  water  must  be  carried  low  in 
the  front  gauges  of  port  boilers  and  high  in  front  gauges  of  star- 
board boilers,  and  vice  versa.  If  oil  appears  in  the  gauges  it  is 
an  indication  that  the  surface  blow  must  be  used.  If  for  any 
reason  salt  water  is  used  in  the  boilers,  the  saturation  must  be 
taken  once  a  watch  (or  oftener)  and  the  density  not  allowed  to 
exceed  -g^-  When  blowing  simply  to  reduce  the  saturation,  the 
bottom  blow  is  always  used,  as  the  coldest  water  is  then  blown  out. 
Having  shut  ofT  the  feed  open  the  blow  very  gradually  and  allow 
the  water  level  to  sink  near  the  bottom  of  the  glass.  If  the 
weather  is  rough  or  the  ship  has  a  list  it  may  be  necessary  to 
pump  up  the  boiler  above  the  natural  level  and  only  blow  down 
to  that  level.  The  water  gauges  must  be  blown  through  occa- 
isonally  to  clear  them  out,  and  the  test  cocks  used  frequently  as 
a  check  on  them.  If  there  is  much  difiference  in  the  pressure 
indicated  by  steam  gauges  of  different  boilers  the  cause  must  be 
discovered.  It  sometimes  happens  that  stop  valves  become  partly 
closed  by  accident. 

The  thickness  of  the  fires  must  be  kept  proportioned  to  the 
strength  of  draught.  Increase  of  draught  has  a  tendency  to  raise 
the  water  level  and  a  decrease  to  lower  it;  therefore  when  work- 
ing under  strong  forced  draught  when  it  is  desired  to  reduce 
speed,  half  an  hour's  notice  should  be  given,  the  draught  grad- 
ually reduced  during  that  time  and  more  water  pumped  in.  If 
necessary  to  stop  the  engines  suddenly,  get  rid  of  surplus  steam 
with  bleeders  or  safety  valves,  or  both.  On  the  other  hand  half 
an  hour's  notice  should  be  given  before  putting  the  blowers  on 
full.  In  the  meantime  fires  must  be  built  up  thick  and  water 
level  reduced,  otherwise  air  will  be  blown  through  the  grates  and 
water  may  be  lifted  so  high  as  to  go  over  into  the  engine.  Coal 
must  be  used  alternately  from  top  and  bottom  bunkers  in  order 
that   the   metacentric   height  of  vessel   mav   not  be   altered.     It 


PROBLEMS,    NOTES    AND    SKETCHES.  IO3 

Tnust  also  be  used  equally  from  both  sides  of  vessel  and  taken 
as  it  comes,  not  picked  over. 

Water  in  boilers  must  be  tested  for  acidity  with  blue  litmus 
paper  every  24  hours.  If  found  acid  put  a  few  pounds  of  car- 
bonate of  soda  into  feed  tank  from  time  to  time  until  the  acidity 
is  corrected. 

The  double  bottoms  in  fire  room  must  be  sounded,  tempera- 
ture of  fire-rooms  and  bunkers  taken  every  watch,  the  regula- 
tions with  regard  to  use  of  lamps  in  bunkers  enforced,  a  close 
watch  must  be  kept  on  water  in  bilge  and  the  strainers  must  be 
kept  clear.  At  sea  make  a  practice  of  keeping  all  W.  T.  doors  in 
bunkers  closed,  as  far  as  practicable. 

Starting  an  Additional  Boiler. 

Proceed  as  before  described  for  getting  up  steam,  except  in 
this  case  the  main  safety  valve  must  be  raised  to  allow  escape 
of  hot  air,  and  must  be  lowered  again  when  steam  forms.  The 
boiler  stop-valve  cannot  be  eased  ofif  its  seat,  so  if  it  is  a  globe 
valve  it  will  probably  stick  fast  when  hot.  When  it  is  desired  to 
open  this  valve,  slack  back  the  nuts  on  the  yoke  about  half  a 
turn,  open  the  valve  a  very  little,  then  screw  up  the  nuts.  Great 
care  must  be  taken  not  to  connect  up  this  boiler  until  the  fires 
have  thoroughly  burned  up  and  are  in  condition  to  make 
steam  and  the  pressure  is  equal  to  or  greater  than  that  on  the 
other  boilers.  Drain  the  branch  pipe  between  the  boiler  and 
stop  valve,  also  stop  valve  chamber.  Do  not  open  the  valve 
wide  at  first  but  unseat  it  until  steam  is  heard  to  pass  through, 
then  leave  it  alone  for  a  few  minutes  before  opening  to  normal 
■width.  While  this  is  going  on  watch  the  index  of  the  gauge 
closely  to  observe  if  there  are  any  violent  fluctuations.  Also 
watch  the  water  gauge  to  see  if  there  is  any  tendency  to  lift  water. 
If  there  is,  shut  ofif  the  stop  valve  partly  or  wholly  until  these 
fluctuations  cease.  Neglect  of  the  foregoing  precaution  is  liable 
.to  be  attended  with  loss  of  life. 

To  Disconnect  a  Boiler. 

Allow  the  lires  to  burn  down  as  if  for  cleaning,  keeping  them 
levelled  ofif.  When  it  is  judged  that  they  will  make  no  more 
steam,  close  the  stop-valve,  partly  close  ash-pit  doors,  and  shut 


I04  MARINE  engines: 

off  feed  and  blow.  When  fires  have  almost  burned  out  close  ash- 
pit doors  completely.  If  steam  should  rise  above  the  limit  the 
boiler  stop-valve  may  be  opened  for  a  minute,  then  closed.  If 
there  is  any  evidence  of  the  presence  of  oil  in  the  boiler  the  sur- 
face blow  should  be  used  to  get  rid  of  it  so  that  when  the  boiler 
is  finally  emptied  a  layer  of  oil  will  not  be  deposited  on  the  in- 
terior. When  fires  are  out  the  furnaces  must  be  hauled  and 
may  then  be  primed  if  there  is  any  chance  of  the  boiler  being- 
wanted  again.  Before  priming  be  sure  that  the  grate  bars  are 
not  hot  enough  to  set  the  coal  on  fire. 

Preparations  for  Coming  into  Port. 

Upon  receiving  notice  that  the  ship  will  come  to  anchor  at  a 
given  time  regulate  the  firing  so  that  the  fires  may  burn  down  as 
much  as  possible,  having  due  regard  to  the  necessity  of  keeping 
steam  to  manoeuvre  the  ship.  ^lake  an  exact  estimate  of  the 
amount  of  coal  on  hand,  allowing  for  what  will  be  required  to 
reach  port.  If  there  is  no  auxiliary  boiler  select  some  one  main 
boiler  to  be  used  in  port,  choosing  one  that  has  been  used  least, 
provided  it  does  not  require  repairs  and  is  not  adjacent  to  one 
which  must  be  entered,  and  provided  also  that  steam  connections 
are  such  that  it  may  be  kept  connected  with  the  auxiliary  steam 
pipe  service,  while  making  repairs  to  leaky  joints  and  sections 
of  pipe  or  overhauling  boiler  stop-valves  that  may  require  such 
attention.  Make  an  inspection  to  see  if  the  list  of  repairs  re- 
ported to  be  necessary  is  correct  and  complete.  Look  at  the 
escape  pipes  to  see  if  any  of  the  main  safety  valves  are  leaking, 
also  inspect  steam  whistle  and  siren.  If  there  is  more  coal  out 
than  is  necessary  return  it  to  the  bunker  or  heap  it  in  front  of 
the  boiler  which  is  to  be  used  in  port.  Shut  any  additional  water- 
tight doors  in  bunkers  that  may  be  found  unnecessarily  open. 
Send  up  all  ashes  without  regard  to  the  hour.  If  there  is  an 
auxiliary  boiler  to  be  used  instead  of  a  main  boiler,  start  fires 
in  it  in  time  to  allow  steam  to  form  and  rise  slowly  to  the  re- 
quired pressure  by  the  time  that  steam  on  the  main  boilers  is 
used  up.  which  will  be  about  an  hour  or  two  after  arriving  in 
port.     Have  coal  ready  to  send  up  for  use  in  the  steam  launch. 

Arrival  in  Port. 

Upon  receiving  word  that  the  engines  will  no  longer  be  re- 
quired the  fires  are  allowed  to  die  out  in  all  except  the  boiler  to> 


PROBLEMS,  NOTES  AND  SKETCHES.  IO5 

be  used  for  auxiliary  purposes;  the  ash-pit  doors  partly  closed 
and  dampers  wholly  shut.  When  after  about  12  hours  time  the 
fires  are  out  they  may  be  quickly  hauled  and  the  furnace  and 
ash-pit  doors  again  shut.  The  time  required  for  the  boilers  to 
cool  will  vary  with  the  size  and  other  conditions,  being  about  36 
to  48  hours  for  single-ended  Scotch  boilers  12X12  feet.  If  pos- 
sible, work  on  the  boilers  should  be  postponed  until  they  have 
cooled  ofif.  If  for  any  reason  it  becomes  necessary  to  blow  down 
a  boiler  at  once,  shut  it  oflf  from  the  others,  raise  the  safety  valves 
until  the  steam  pressure  has  fallen  to  about  25  or  30  pounds  in 
excess  of  pressure  of  water  overboard  at  the  level  of  the  bottom 
blow.  Blowing  then  will  cause  less  jar  and  shock  to  boilers  and 
pipes. 

While  waiting  for  the  boilers  to  cool  the  fire  tools  may  be  re- 
paired, slice  bars  straightened,  new  heads  put  on  hoes,  shovels 
trimmed  and  coal  bunkers  repaired.  Work  (hereafter  to  be 
described)  on  bunkers,  etc.,  may  be  done. 

If  there  is  no  work  to  be  done  on  a  boiler  which  necessitates 
pumping  out,  if  the  water  is  fresh  and  not  very  greasy,  it  should 
be  left  in. 

Cleaning  Boilers  Outside. 

When  the  boiler  is  cool,  sweep  tubes,  remove  grate  bars  and 
clear  them  of  slag  and  clinkers.  Clear  out  combustion  chambers, 
furnaces,  and  ash-pits.  Inspect  the  tube  sheets  and  make  a 
record  of  the  number  and  position  of  all  leaky  tubes,  seams, 
rivets,  etc.  Then  scale  the  tube  sheets,  plates  in  vicinity  of  leaky 
seams  and  rivets  in  order  that  the  tubes  may  be  expanded  and 
leaks  caulked.  Examine  all  stay  rods  (if  any)  through  tubes  and 
try  nuts  with  wrench  to  see  if  they  are  too  tight  or  too  loose. 
Also  clean  plates  on  outside  of  boilers  in  vicinity  of  leaky  seams 
and  rivets.  If  work  requires  it,  now  pump  out  the  boilers  and 
proceed  to  expand  tubes,  cut  out  leaky  ones  as  required,  caulk 
rivets,  seams,  etc.  Salt  in  the  tubes  may  be  softened  by  turn- 
ing in  a  jet  of  steam  for  several  hours.  Salt  in  ash-pits  is  soft- 
ened by  building  a  dam  of  ashes  and  filling  pit  with  fresh  water 
allowing  it  to  stand  overnight. 

Scaling  Boilers. 

Do  not  open  boilers  until  ready  to  scale  them,  as  contact  with 
the  air  hardens  the  scale  and  makes  it  stick.     When  ready  open 


io6  MARINE  engines: 

the  drain  cocks.  Remove  all  man  and  hand-hole  plates,  and 
lower  a  lamp  into  the  boiler  to  see  if  the  air  is  respirable.  If  not, 
wait  until  the  foul  air  escapes.  Stop  with  wooden  plug^s  all  open- 
ings of  pipes  in  lower  part  of  boiler  in  order  that  they  may  not 
become  choked  with  scale.  Then  proceed  with  scaling  as  quickly 
as  possible,  taking  care  not  to  remove  scale  from  any  but  heating 
surfaces.  The  back  tube  sheets,  crown  sheets,  and  the  junction 
of  the  two  require  the  greatest  attention. 

After  scaling  and  before  washing  out  is  the  time  to  do  any 
work  that  may  be  necessary  inside.  Inspect  the  zinc  plates  and 
renew  them  if  they  are  one-half  used  up.  These  plates  should 
be  supplied  at  the  rate  of  one  for  every  30  I.  H.  P.,  the  size  being 
12"  X  6"  X  i"-  If  the  metallic  connections  with  l)races  or  boiler 
have  rusted  file  off  the  rust.  Examine  all  internal  pipes  and  their 
supports.  When  scaling  and  other  work  is  completed,  haul  out 
the  refuse  from  the  bottom  of  boilers  with  light  hoes  provided 
for  the  purpose,  then  wash  out  the  interior  with  steam  fire  hose. 
Finally  remove  wooden  plugs  which  were  put  in  the  pipes  and 
replace  all  plates,  using  same  gaskets  if  good  and  putting  on 
fresh  black  lead  or  chalk  on  one  side  and  paint  on  the  other  if 
required.  If  gasket  is  not  good,  scrape  bearing  surface  on  plate 
clean,  paint  it  with  red  lead  and  lay  the  rubber  gasket  in  place. 
Then  cover  other  surfaces  of  gasket  with  black  lead  or  chalk. 
If  the  plate  does  not  fit  well,  Tuck's  packing  makes  a  good 
gasket,  thinning  down  and  lapping  the  ends  and  wedging  it  in 
the  angle  between  the  fiat  bearing  surface  and  the  ridge  on  the 
inner  side  of  plate.  Asbestos  cardboard  Ys"  thick  soaked  in 
boiled  linseed  oil  is  excellent,  taking  care  to  black-lead  the  sur- 
face which  bears  against  the  boiler.  Sometimes,  especially  with 
auxiliary  boilers  and  those  of  the  locomotive  marine  type,  all 
parts  of  the  interior  are  not  accessible  for  cleaning  and  scaling, 
and  cannot  be  reached  even  with  a  stream  from  a  hose.  In  such 
cases  the  cleaning  is  completed  by  boiling  out  with  solutions  of 
soda  and  milk  of  lime.  Pump  up  the  water  to  the  top  of  the 
glass,  then  introduce  through  a  cock  provided  for  the  purpose,  or 
else  througfh  a  man-hole  plate,  a  couple  of  pounds  of  soda  and 
an  equal  quantity  of  lime  dissolved  in  water.  Then  get  up  a 
pressure  of  steam  to  30  or  45  pounds  and  boil  four  to  six  hours. 
An  emulsion  will  be  formed  and  will  float  on  the  surface  and 
must  be  blown  off  through  the   surface  blow.     After  this   the 


PROBLEMS,    NOTES    AND    SKETCHES.  IO7 

boiler  must  be  cooled,  emptied,  and  the  bottom  cleared  of  the 
deposit  which  will  be  found  there.  In  case  of  coil  boilers,  es- 
pecially the  small  ones  vised  in  launches,  a  pint  of  kerosene  intro- 
duced in  the  feed  water  from  time  to  time  while  the  boiler  is 
imder  steam,  is  most  efficient  in  softening  deposits,  especially  oily 
ones. 

Now  take  up  the  boiler  fittings,  grinding  in  the  cocks  and 
valves,  packing  valve-stem  stuffing  boxes,  etc..  and  examine  main 
safety  valve,  unless  it  has  been  done  within  the  past  six  months. 

Filling  Boilers. 

When  all  repairs  inside  and  out  are  completed  and  grate  bars 
cleaned  and  replaced,  take  advantage  of  the  first  opportunity  to 
fill  the  boilers  with  fresh  water,  either  from  shore  or  from  the 
evaporator.  The  former  is  much  cheaper  and  the  latter  rather 
better  for  the  boilers. 

The  regulation  with  regard  to  using  the  boilers  to  trim  ship  has 
sometimes  been  disregarded  on  account  of  the  difficulty  in  keep- 
ing a  modern  ship  on  an  even  keel  without  using  them. 

Light  wind  abeam  when  swinging  to  tide,  lowering  one  boat 
more  on  one  side  than  the  other,  mustering  the  crew  on  port  side 
of  quarter  deck,  water  in  double  bottoms,  emptying  a  boiler  on 
one  side  or  the  other  for  repairs,  pumping  fresh  water  out  of  a 
boiler  for  use  in  the  auxiliary,  are  among  the  most  frequent  causes 
of  a  ship's  list.  If  the  coal  used  for  auxiliar}-  purposes  is  taken 
alternately  from  starboard  and  port  bunkers  every  twelve  hours, 
there  need  never  be  any  trouble  from  this  cause. 

In  former  times  the  guns  were  run  in  and  out  or  the  heavy 
forward  pivot  gun  shifted  to  keep  the  ship  upright,  but  with  the 
modern  guns  as  placed  this  cannot  be  well  done.  If  the  regula- 
tion is  to  be  enforced,  the  boilers  should  be  filled  to  the  top  for 
better  preservation.  Otherwise  it  is  better  to  fill  them  to  steam- 
ing level  to  allow  a  margin  to  vary  the  level  up  or  down  to  trim 
ship.  Boilers  are  generally  filled  by  using  a  feed  pump,  the  fresh 
water  being  run  into  the  feed  tank  from  a  hose  connected  with 
a  pump  on  a  water  lighter  or  hydrant  on  the  dock.  In  filling  a 
boiler  with  fresh  water,  bicarbonate  of  soda  should  be  put  in  as 
the  water  is  entering  the  boiler — about  a  pound  of  soda  (dissolved 
in  water)  for  each  ton  of  water  in  the  boiler. 

If  the  upper  man-hole  plates  are  off  it  is  sometimes  simpler  to 


io8  MARINE  engines: 

turn  the  hose  in  direct.  If  for  any  reason  salt  water  is  to  be 
used  it  is  run  in  through  the  bottom  blow,  first  opening  the  air 
cock,  or  lifting  the  safety  valve  to  let  out  the  air.  Avoid  filling 
the  boilers  in  this  manner  at  ebb  tide  in  a  river  or  when  the  water 
in  a  harbor  is  dirty.  After  the  boilers  are  filled,  never  before, 
furnaces  mav  be  primed,  but  this  is  better  postponed  until  about 
to  get  up  steam,  as  it  checks  circulation  of  air  through  furnaces, 
thus  leading-  to  deposits  of  moisture  and  rust.  The  dampers 
should  be  kept  open  and  ash-pit  doors  ofif.  Smoke  pipe  cover 
must  be  kept  off  in  fine  weather,  and  must  be  put  on  and  the 
fire-room  hatches  covered  before  rain.  Paint  on  front  connec- 
tion doors,  uptakes,  boiler  shell  where  accessible,  smoke  pipe, 
etc.,  must  be  renewed  from  time  to  time,  vising  red  lead  or  brown 
zinc  as  a  priming  coat.  See  that  decks  over  boilers  do  not  leak 
and  that  the  bilges  underneath  are  kept  dry.  In  damp  weather 
drying  stoves  are  kept  burning  in  fire-rooms  where  there  is  no 
steam,  changing  them  from  boiler  to  boiler.  The  same  in  freez- 
ing weather  if  the  temperature  falls  near  freezing  point. 

Coal  Bunkers. 

When  work  on  boilers  is  completed,  the  next  thing  in  order 
is  to  inspect  the  coal  bunkers.  Before  entering  a  large,  badly 
ventilated  bunker,  the  air  should  be  tested  by  introducing  a  safety 
lamp.  A  blue  flame  on  the  outside  of  the  wire  gauze,  or  the 
lamp  becoming  extinguished,  indicates  the  presence  of  an  ex- 
plosive gas  and  the  bunker  requires  further  ventilation.  Care 
must  be  taken  that  the  door  of  the  lamp  shuts  tight  and  that  there 
is  no  accumulation  of  soot  on  the  inside,  otherwise  it  will  fail  to 
act  and  cause  an  explosion. 

The  fittings  of  water-tight  doors  are  to  be  overhauled,  coaling 
ports  and  bunker  deck  plates  made  tight,  valves  and  pipes  for 
extinguishing  fire  put  in  order,  and  broken  braces  renewed.  Scale 
and  paint  inside  and  out  where  required,  put  electric  lights  and  fire 
alarm  apparatus  in  order  and  clear  bunker  drains.  The  outer 
wall  of  lower  bunkers  being  part  of  the  skin  of  the  ship  and  in 
contact  with  water  outside,  is  cold  and  condenses  moisture  to 
such  an  extent  that  it  is  seldom  dr>'  enough  to  paint  unless  the 
temperature  of  the  external  air  being  less  than  that  of  the  water, 
allows  the  air  in  the  bunker  to  be  sufificiently  cooled  or  the  ship 


PROBLEMS,    NOTES    AND    SKETCHES.  109 

is  in  dry  dock,  in  which  latter  case,  the  bunker  is  often  inacces- 
sible from  being  partly  filled  with  coal.  Even  if  painted  the  paint 
is  soon  knocked  ofif  by  coal  striking  the  inclined  surfaces  when 
thrown  down  from  the  upper  bunkers.  Probably  the  best  thing 
to  do  is  to  wipe  over  the  surfaces  occasionally  with  waste  dipped 
in  mineral  oil.  \M'ien  the  work  and  painting  are  done,  get  the 
bunkers  ready  for  coaling  by  restowing  coal  where  necessary  in 
such  a  manner  as  to  facilitate  receiving  an  additional  quantity. 
Bunkers  must  always  be  kept  well  aired  by  using  the  gratings 
instead  of  deck  plates  as  much  as  possible,  being  careful  to  put 
on  the  plates  every  morning  before  the  decks  are  washed.  Also 
keep  as  many  of  the  water-tight  doors  open  as  possible  during 
the  day  and  shut  them  at  night. 

Fire  Room. 

While  at  work  on  bunkers,  the  pumps  in  the  fire  room,  sluice 
valves,  strainers,  and  valves  for  pumping  out  the  compartments, 
may  be  put  in  order. 

Double  Bottoms. 

The  last  work  will  be  cleaning  and  drying  out  the  double  bot- 
toms, and  renewing  the  cement  and  paint  as  required.  Before 
entering  a  compartment  let  down  an  open  light.  If  it  does  not 
burn  brightly,  the  compartment  must  be  ventilated;  this  is  easily 
done  after  the  man-hole  plate  is  removed,  by  starting  the  com- 
partment pump  as  if  to  pump  out  water.  If  as  sometimes  hap- 
pens there  are  no  pipes  for  pumping  out  the  compartments,  a 
small  blower  should  be  procured  and  provided  with  a  flexible  hose 
to  discharge  air  into  the  compartments. 

In  the  English  navy  most  elaborate  precautions  are  taken  to 
prevent  men  employed  in  painting  confined  spaces,  such  as  double 
bottoms,  from  suffering  from  lead  poisoning.  No  such  precau- 
tions are  taken  in  our  navy,  nor  do  they  appear  necessar\\  How- 
ever it  is  well  to  furnish  the  surgeon  with  a  list  of  the  men  em- 
ployed in  order  that  he  may  keep  a  lookout  for  any  symptoms 
and  use  necessary  preventative  measures  in  good  time. 

While  laying  on  the  cold  iron  the  men  should  have  a  piece  of 
rubber  or  canvas  under  them  to  prevent  getting  rheumatism. 

Finallv  clean  fire-room  bilges,  clear  strainers,  etc. 


no  MARINE    engines: 

MANAGEMENT  AND  CARE  OF  THE  MAIN  ENGINES 
AND  AUXILIARIES. 

(Chap.  XXX.,  S.  &  O.) 

Preparing  to  get  Underway. 

Art.  34. — When  preparing  to  get  underway,  delays  may  be 
occasioned  by  a  gasket  blowing  out,  a  valve  coming  ofif  its  stem^ 
a  lever  or  screw  sticking,  cylinder  relief  valve  spring  breaking, 
stuffing  boxes  leaking,  etc.  For  this  reason  it  is  a  good  plan  to 
arrange  to  have  all  the  necessary  auxiliary  engines  ready,  and  to 
turn  the  main  engines  about  an  hour  before  the  time  appointed 
to  get  underway.  On  medium  and  large  ships  this  will  make 
it  necessary  to  begin  preparations  about  two  hours  before  the 
time  set  for  getting  tuidcrtvay.  Generally  the  first  thing  to  do^ 
is  to  get  the  capstan  ready  and  turn  steam  on,  as  that  engine 
may  be  wanted  to  "  heave  short  "  or  "  unmoor,"  some  time  before 
getting  up  anchor.  It  is  to  be  understood  that  all  steam  engines 
of  whatever  size  are  to  be  oiled  and  drained  before  they  are 
started.  The  greater  the  emergency,  the  more  important  it  is 
to  take  these  precautions,  otherwise  the  engine  is  liable  to  be  dis- 
abled just  when  most  required  for  use.  The  work  of  getting 
ready  is  divided  between  the  machinists  and  oilers,  each  of  the 
latter  reporting  to  the  machinist  in  charge  when  all  is  ready  on 
his  station.  If  there  are  not  enough  men  on  the  watch,  part  of 
the  relief  is  called  and  kept  until  fairly  underway.  A  man  should 
he  stationed  at  the  speaking  tube  during  the  whole  time.  If  water 
is  liable  to  be  used  on  the  crank  pins,  it  is  a  good  plan  to  cover 
all  iron  bright  work  in  their  vicinity  with  a  coat  of  white  lead  and 
tallow.  A  coat  of  tallow  is  sometimes  put  on  inaccessible  parts 
in  order  that  the  melting  of  the  tallow  may  afiford  a  means  of 
judging  if  the  part  is  getting  warm. 

Open  the  outboard  delivery  and  injection  and  start  the  circu- 
lating pump;  then  start  the  air  pump.  Turn  steam  on  the  cylin- 
der jackets,  if  any,  and  drain  them,  start  the  engine  stop-valves- 
ofif  their  seats,  allowing  the  hot  air  and  steam,  which  at  this  time 
should  have  begun  to  form  in  the  boilers,  to  pass  through  the 
cylinders  and  into  the  condenser.  Besides  warming  the  cylinders 
the  steam  will  serve  to  form  a  vacuum  in  the  condenser.  See  that 
the  drains  of  the  cvlinders  and  steam   chests  are  open.     They 


PROBLEMS,  NOTES  AND  SKETCHES.  Ill 

should  be  shut  when  steam,  instead  of  water,  begins  to  come 
out.  If  the  engines  are  3000  I.  H.  P.  or  larger,  an  hour  may, 
with  advantage,  be  employed  in  warming  them  up  gradually. 
See  that  nothing  is  stored  about  the  working  parts  of  the  engine 
and  that  there  is  nothing  loose  about  the  engine  room  likely  to 
get  into  contact  with  the  working  parts  when  the  ship  rolls;  see 
that  all  set  bolts  and  split  pins  on  the  moving  parts  are  all  in 
place.  Remove  the  gaskets  from  the  ends  of  the  journals  and 
see  that  the  turning  engine  is  disconnected.  Fill  the  oil  cups 
and  cans  and  see  that  the  wicks  are  in  order,  and  that  the  oil 
pipes  are  clear.  It  is  well  to  put  in  the  wicks  long  enough  before 
the  engine  is  turned,  to  allow  oil  to  trickle  down  naturally  and 
flow  over  the  journals.  If  in  a  hurry  pour  some  oil  down  the 
pipes  from  a  squirt  can  or  feeder.  As  the  oilers  make  the  rounds 
they  should  keep  a  lookout  for  loose  bolts,  nuts,  keys,  set  screws, 
oil  cups,  etc.  Also  slacken  the  nuts  of  the  stern  stuffing  box 
gland.  If  there  is  a  clutch  coupling,  see  that  it  is  coupled  up 
properly ;  neither  too  tight  or  too  loose ;  that  the  brake  is  slackened 
and  secured  and  all  loose  articles  in  the  shaft  alley  stored  for  sea. 
Try  all  valves  on  the  water  service  to  see  if  water  will  flow 
through,  then  shut  the  main  supply  valve  and  leave  the  one  gen- 
erally required  open,  so  that  when  the  engine  is  started  water  may 
be  turned  on  by  simply  opening  one  valve. 

Examine  bilge  pump  and  bilge  injection  strainers;  warm  up 
and  try  the  reversing  engine. 

Turn  steam  on  steering  engine  and  try  it;  also  try  the  steam 
whistle,  syren,  engine  room  telegraph  and  gongs.  The  last  gen- 
erally has  several  bell  pulls  placed  in  different  parts  of  the  ship. 
Try  them  all.  On  some  ships  the  whistles  and  bells  are  tried  by 
the  officer-of-the-deck.  There  should  be  a  distinct  understand- 
ing beforehand  as  to  whose  duty  this  is:  better  a  written  memoran- 
dum.^ 

In  case  of  an  engine  with  two  cranks  and  a  variable  cut-off,  it 
is  generally  necessary  to  run  the  cut-off  out  about  full  stroke,  in 
order  that  the  engine  may  be  started  promptly.  In  case  of  com- 
pound or  triple  expansion  engines,  it  is  well  to  be  ready  to  let  a 
little  live  steam  into  the  receiver,  the  amount  being  found  by  experi- 
ment. 

When  all  the  foregoing  preparations  have  been  made  and  in- 
spected by  the  engineer  on  duty  and  the  steam  pressure  in  the 


112  MARINE    engines: 

boilers  is  high  enough,  get  permission  from  the  officer-of-the 
deck  to  turn  the  engines  and  pass  the  word  around  the  engine- 
room  to  "  stand  clear."  When  the  engines  are  being  tried  a  look- 
out should  be  kept  on  deck,  since  the  effect  upon  the  ship  of  the 
motion  of  the  screw  cannot  be  observed  from  below,  and  it  varies 
considerably  with  wind  and  tide.  When  possible,  the  engines 
should  make  a  number  of  turns  each  way  to  work  the  water  out 
of  the  cylinders.  If  no  special  lookout  is  kept  on  deck,  never 
make  more  than  two  or  three  turns  in  one  direction  before  re- 
versing the  engine.  In  any  case  the  engine  should  be  worked 
slowly.  If  all  is  found  to  work  well  and  the  vacuum  in  the  con- 
denser is  as  high  as  usual,  shut  the  main  engine  throttle  valve  and 
put  the  links  in  mid-position. 

Now  make  an  inspection  of  the  engine  and  fire-rooms,  see  that 
all  men  are  at  their  stations ;  that  none  have  neglected  their  duties ; 
that  there  are  no  signs  of  leaks  starting  in  boilers  or  pipes;  and 
that  the  auxiliaries  are  all  working  in  a  normal  manner. 

When  the  time  set  for  getting  underway  arrives,  report  to  the 
chief  engineer,  who  reports  to  the  commanding  officer,  that  the 
engines  are  ready.  Then  get  a  pump  ready  to  start  promptly 
on  the  lire-main  as  the  hose  will  be  used  to  wash  off  the  anchor 
and  chain. 

If,  after  all  is  ready,  the  time  for  getting  underway  is  postponed 
several  hours,  the  wicks  should  be  taken  out,  steam  shut  off  the 
capstan  and  steering  engines;  air  and  circulating  pumps  slowed 
down.  If  the  fires  are  under  complete  control  and  there  is  no 
chance  that  the  bleeders  will  be  required,  these  pumps  may  be 
stopped  and  the  outboard  valves  closed. 

Underway. 

Upon  receipt  oi  orders  to  stand  by  to  get  underiuay,  a  machinist 
should  stand  by  the  reversing  gear  and  an  oiler  or  other  rel,iable 
man  at  the  engine  room  telegraph  and  voice  tube  and,  if  neces- 
sary, another  at  the  throttle.  Start  the  engines  slowly  and  allow 
about  five  minutes  for  gradually  opening  out  to  full  speed.  After 
this  a  machinist  must  always  be  stationed  at  the  reversing  gear 
until  arrival  in  port  and  at  anchor,  unless  relieved  by  some  com- 
petent and  authorized  man  who  has  had  experience  in  handling 
the  engines.  When  underway,  keep  a  close  watch  on  all  parts  of 
the  engines  that  have  been  adjusted  since  the  last  run,  until  sure 
that  these  parts  wall  not  heat. 


PROBLEMS,    NOTES    AND    SKETCHES.  II3 

After  the  engines  are  fairly  underway  and  the  ship  well  clear 
of  the  land,  the  cut-ofifs,  if  previously  run  out  to  facilitate  hand- 
ling the  engines,  are  now  adjusted  to  insure  greater  economy 
of  steam  consistent  with  smooth  working  of  the  engines. 

For  economy,  the  terminal  pressure  in  the  L.  P.  cylinder  should 
be  equal  to  the  back  pressure  plus  the  pressure  required  to  over- 
come the  friction,  or,  roughly  speaking,  it  should  be  a  few  pounds 
above  the  back  pressure. 

Economy  is  perceptibly  increased  by  linking  up,  thus  increas- 
ing the  compression  and  partly  filling  the  clearance  spaces.  As 
this  shortens  the  travel  of  the  valve,  it  will  ultimately  (after  a 
number  of  years)  wear  a  ridge  on  the  valve  seat  which  will  have 
to  be  scraped  down.  As  it  also  reduces  the  port  opening,  it  must 
not  be  done  in  those  few  rare  cases  where  naval  vessels  are 
worked  at  full  power. 

Theory  and  experiment  both  show  that,  with  compound  or 
triple  expansion  engines,  it  is  much  more  economical  to  work 
with  full  boiler  pressure  and  cut-off  short,  than  to  carry  a  re- 
duced boiler  pressure  and  throttle  down  with  cut-ofTs  run  out. 

Smoothness  of  working  is  generally  to  be  obtained  by  linking 
up.  As  naval  engines  often  work  at  about  one-fifth  power,  the 
pressure  in  the  L.  P.  cyl.  is  so  small  that  linking  up  has  no  eiTect. 
In  such  cases  the  engines  will  work  more  smoothly  if  run  at  a 
higher  speed,  or,  if  this  cannot  be  done,  by  carrying  less  vacuum 
and  higher  temperature  in  the  hot  well.  After  all  adjustments 
have  been  made,  indicator  cards  should  be  taken  to  make  sure 
that  all  is  going  on  in  the  cylinders  as  intended. 

A  general  inspection  should  now  be  made  throughout  the  de- 
partment, taking  particular  care  to  see  that  the  bilge  pump  is 
working  and  its  strainer  is  clear.  The  order  "  full  speed  "  is  to 
be  understood  as  the  greatest  speed  that  can  be  made  with  the 
boilers  and  fires  in  use  at  the  time. 

The  order  to  change  from  full  speed  in  one  direction  to  full 
speed  in  the  other,  should  never  be  given  except  in  great  emer- 
gencies. The  engines  should  be  slowed  down  and  stopped  before 
reversing.  But  if  the  order  to  change  from  full  speed  in  one 
direction  to  full  speed  in  the  other  should  be  given,  it  must  be 
executed  promptly  at  the  risk  of  breaking  the  shaft. 

x\fter  the  engines  are  started,  it  is  a  matter  of  pride  to  keep  them 
going  to  the  end  of  the  voyage.  This  requires  close  watch  to 
s 


114  MARINE    engines: 

anticipate  and  prevent  any  accidents.  Also  some  ingenuity  in 
repairing  and  correcting  defects  as  they  appear.  If  it  should  be- 
come necessary  to  slow  down  or  stop,  always  give  the  ofiticer-of- 
the-deck  as  long  notice  as  possible  in  order  that  he  may  inform 
the  commanding  officer,  and  the  latter  decide  what  to  do.  All 
reports  of  this  kind  should  be  accompanied  with  a  statement  of  the 
nature  of  the  difficulty,  the  probable  length  of  time  before  the 
engines  will  be  ready  to  go  ahead  again  at  their  former  speed, 
and  any  other  information  that  will  be  of  service  to  the  com- 
manding officer  in  aiding  him  to  come  to  a  decision  with  regard 
to  what  he  is  to  do  with  the  ship.  The  chief  engineer  must  be 
notified  at  the  same  time.  In  case  it  should  be  necessan,-  to  stop 
the  engine  before  the  officer-of-the-deck  can  be  notified,  he  must 
be  informed  as  soon  as  possible  afterwards.  Use  the  engine  room 
telegraph,  voice  tube,  messenger,  in  the  order  named.  While  the 
engines  are  running,  everyone  in  the  engine  room  must  keep  a 
watch  on  all  gauges,  thermometers,  counters,  stuffing  boxes,  bear- 
ings, etc.,  and  listen  to  the  combination  of  sounds  made  by  the 
various  working  parts  and  called  by  the  French  "  le  chant  de  la 
machine."  Any  changes  in  the  indications  of  the  gauges,  or 
variation  of  any  of  the  normal  sounds,  must  be  investigated  and 
the  causes  ascertained.  When  a  gauge  gives  a  peculiar  indica- 
tion, first  see  whether  it  is  shut  off  or  out  of  repair.  Turn  the 
cock  on  full,  then  shut  it  off  and  wait  until  the  index  falls  to  zero. 
Test  a  thermometer  by  using  another  in  the  same  place.  If  a 
stuffing  box  leaks,  take  notice  if  the  leak  is  all  on  one  side;  if  so 
the  rod  may  be  out  of  line,  and  the  stuffing  box  gland  should 
not  be  set  up  tight.  If  there  is  a  slight  dew  on  large  brasses,  they 
cannot  be  hot.  If  there  is  a  lather  formed  at  the  ends  of  the  jour- 
nals they  are  properly  lubricated  and  cool.  If  there  is  no  lather, 
but  the  oil  running  out  is  discolored  by  the  abrasion  of  metal, 
the  lubrication  is  insufficient.  If  the  oil  runs  out  clear  and  un- 
changed in  appearance,  the  supply  is  too  great. 

A  great  deal  of  information  with  regard  to  the  running  of  an 
engine  may  be  obtained  by  the  sense  of  hearing.  First  the  sounds 
may  be  divided  into  two  general  classes,  the  normal  and  the  ab- 
normal. Among  the  former  may  be  mentioned  a  leading  thump 
of  one  of  the  crank  pin  brasses  as  the  pin  passes  one  dead  point. 
It  rarely  happens  that  all  the  crank  pin  brasses  are  so  evenly 
adjusted  that  some  journal  does  not  make  more  noise  than  an- 


PROBLEMS,    NOTES    AND    SKETCHES.  II5 

Other.  Then  there  is  the  shp  of  the  Hnk  block  in  the  Unk,  the 
steam  flowing  into  the  valve  chest,  exhaust  into  the  condenser, 
the  valves  of  the  dififerent  pumps,  periodic  blowing  of  the  traps, 
etc.     The  abnormal  sovmds  will  be  treated  of  later. 

The  two  foregoing  general  classes  may  be  divided  into  sounds 
which  are  coincident  with  the  motion  of  the  main  engines  and 
which  therefore  must  come  from  some  part  connected  with  them, 
and  on  the  other  hand — sounds  not  coincident.  These  two  latter 
classes  may  be  further  divided  into  the  light  tinkling  sounds 
which  must  obviously  be  made  by  looseness  of  some  light  piece, 
and  the  dull  heavy  thuds  which  come  from  heavier  parts.  A 
good  ear  can  also  distinguish  between  the  clear  bell-like  sound 
given  out  by  solid  brass  and  the  less  musical  note  made  by  an 
iron  piece  of  same  weight.  By  keeping  in  mind  the  above  clas- 
sification many  normal  and  abnormal  sounds  may  be  quickly 
traced  to  their  origin.  There  are  some  sounds  so  common  with 
certain  engines  that  they  may  as  well  be  mentioned  here, 
although,  strictly  speaking,  they  should  be  treated  of  with  other 
abnormal  noises. 

First  is  water  in  the  cylinders,  which  causes  a  thump  on  one  or 
both  ends,  and  may  often  be  detected  by  observing  water  gush- 
ing out  around  the  indicator  pipes  and  cocks  and  piston  rod  stuf- 
fing box.  If  suspected,  the  cylinder  relief  valves  or  drain  cocks 
on  the  corresponding  ends  of  the  cylinders  must  be  opened.  If 
as  often  happens,  there  is  no  pressure  in  the  cylinders  the  cut-ofif 
may  be  run  in  until  the  pressure  in  the  receiver  rises  above  the 
atmospheric  pressure,  unless  the  cylinder  drain  connects  with 
the  condenser. 

There  is  another  sound,  a  harsh  rasping  one,  often  heard  in  a 
L.  P.  cylinder  when  the  engines  are  slowed  down  preparatory 
to  entering  port.  It  is  caused  by  a  small  amount  of  water  in  the 
cylinder  and  will  cease  when  the  engine  is  speeded  up  again.  If 
that  noise  should  occur  when  the  engines  are  first  underway,  it 
might  properly  be  attributed  to  the  piston  springs  being  too  tight. 
If  caused  by  a  small  amount  of  water,  it  does  no  harm,  though 
unpleasant  to  listen  to. 

To  discover  in  which  crank  pin  or  main  journal  there  is  a 
thump,  accompanied  by  a  jar  of  the  engine,  take  notice  which 
crank  passes  the  dead  point  when  the  sound  is  heard.  An  addi- 
tional check  is  to  flood  the  journals  in  succession  with  oil  or  water 


Il6  MARINE    engines: 

through  the  oil  pipes,  and  observe  if  the  sound  is  deadened.  First 
try  the  crank  pins,  then  the  crosshead  journals,  then  the  main 
shaft  journals.  If  the  sound  continues,  it  may  be  that  the  oil  or 
water  did  not  get  access  to  the  bearing,  or  else  the  noise  may 
be  due  to  the  piston  being  loose  on  the  rod,  or  the  follower  loose 
on  the  piston.  Thumps  due  to  loose  crank  pin  or  cross-head 
brasses,  loose  piston,  or  loose  follower,  will  be  greatly  reduced 
if  nearly  all  the  load  is  taken  ofT  that  cylinder  by  readjustment 
of  the  various  cut-ofYs.  It  may  also  often  be  reduced  by  linking 
up.  If  it  is  due  to  a  loose  core  plug,  follower  bolt  or  anything 
solid  inside  being  struck  by  the  piston,  the  foregoing  measure 
will  have  no  effect  in  diminishing  the  noise  and  the  engine  must 
be  stopped  as  soon  as  possible.  When  the  piston  springs  are  not 
tight  enough,  they  alternately  contract  and  expand  towards  the 
end  of  the  stroke,  causing  a  knocking  of  the  rings  against  the 
walls  of  the  cylinder,  giving  out  a  clear  metallic  clacking,  with- 
out producing  any  vibrations  in  the  engine  such  as  would  have 
been  observed  if  the  journal  brasses,  piston,  or  follower  were 
loose.  The  only  damage  will  be  leakage  of  steam  and  the  remedy 
may  be  postponed  until  the  arrival  in  port.  Metallic  packing 
sometimes  gets  loose  and  causes  a  clacking  sound  at  the  end  of 
one  or  both  strokes,  which  may  easily  be  mistaken  for  some- 
thing inside  the  cylinder,  especially  if,  at  the  same  time,  the  loose 
packing  causes  a  poor  vacuum,  which  latter  gives  rise  to  a  coin- 
cident jar  of  the  whole  engine  from  the  consequent  change  of 
distribution  of  the  pressures  on  the  piston.  A  sudden  stillness 
pervading  the  engine  room  is  one  of  the  most  alarming  indica- 
tions, for  it  is  a  sign  that  some  large  journal  is  getting  hot.  If 
accompanied  by  an  odor  of  burning  oil  the  indication  is  con- 
firmed. If  a  thump  is  heard  about  the  cylinder  when  the  piston 
is  near  the  middle  of  the  stroke,  it  must  obviously  come  from 
the  slide  valve,  and  is  probably  due  to  the  valve  being  loose  on 
the  stem  or  else  striking  something  at  the  end  of  its  stroke.  If 
the  latter  is  the  case,  the  noise  will  be  stopped  by  linking  up  which 
will  reduce  the  travel  and  make  it  possible  to  continue  working 
the  engine,  although  it  is  advisable  to  stop  as  soon  as  practicable 
to  remove  the  obstruction.  If  due  to  the  cut-ofif  blocks  on  the 
back  of  the  main  valves  striking  something,  the  cut-offs  should 
be  run  out  and  the  steam  regulated  by  throttling. 

A  sharp  clear-cut  sound  of  exhaust  steam  in  the  exhaust  pipes 


PROBLEMS,  NOTES  AND  SKETCHES.  11/ 

indicates  rapid  condensation  and  the  amount  of  the  injection 
may  be  somewhat  reduced.  A  dull  sound  in  steam  or  exhaust 
pipe  is  an  indication  that  the  boilers  are  foaming  or.  at  least,  that 
the  steam  is  wet.  A  thump  at  the  end  of  the  stroke  of  a  circu- 
lating pump  water  piston  indicates  that  the  pump  is  overloaded. 
See  that  the  air  checks  at  the  end  of  the  water  cylinder  are  work- 
ing, and,  if  so,  open  the  regurgitating  valve  or  partly  shut  down 
the  injection  or  slow  the  pump. 

A  thump  in  the  air  pump  may  be  caused  by  one  or  more  valves 
being  carried  away.  If  this  is  the  case  there  will  probably  be 
a  fall  of  vacuvmi  at  the  same  time. 

It  is  a  very  difificult  matter  to  discover  from  which  direction  a 
sound  comes,  owing  probably  to  the  reflection  of  the  sound  waves 
as  they  strike  different  surfaces  of  the  machinery  and  bulkheads, 
and  also  to  the  metal  being  a  better  conductor  than  air.  An  illus- 
tration of  this  is  a  case  where  search  was  made  in  the  rigging 
for  the  cause  of  a  sound  due  to  vibration  of  the  main  injection 
valve  in  thebottom  of  the  ship.  The  true  location  was  discovered 
by  observing  that  it  did  not  coincide  with  the  rolling  of  the  ship 
but  was  exactly  coincident  with  the  motion  of  the  independent 
circulating  pump. 

If  brass  cuttings  are  seen  to  come  from  the  pipe  which  lets  sea 
water  circulate  in  the  stern  tube  and  enter  the  bilge,  it  shows 
that  the  lignum  vitae  strips  have  worn  down  to  the  brass;  the 
propeller  shaft  is  consequently  out  of  line  and  liable  to  break  at 
any  time. 

In  order  to  be  able  to  judge  quickly  and  correctly  the  cause 
of  any  irregularity  in  the  working  of  an  engine  it  is  important  to 
have  a  thorough  knowledge  of  all  the  details  of  its  construction 
and  present  state  of  adjustment. 

Routine  at  Sea. 

Upon  coming  on  watch,  see  that  the  speed  of  the  engines,  po- 
sition of  the  throttle  and  cut-ofT  valves  is  correct,  and  that  all 
steam  and  vacuum  gauges,  thermometers,  etc.,  give  normal  indi- 
cations in  accordance  with  a  table  made  out  from  previous  ex- 
perience. 

See  that  all  journals,  slides,  piston  rods,  valve  stems,  etc.,  are 
properly  lubricated,  water  in  bilge  and  feed  tank  not  too  high 
and  that  bilge  strainers  are  clear.     Each  man  informs  his  relief 


Il8  MARINE    engines: 

of  all  orders  relating  to  that  part  of  the  machinery  under  his 
immediate  care.  The  machinist  should  read  up  the  logs  of  the 
two  preceding  watches  to  see  if  anything  unusual  has  occurred, 
in  case  his  predecessor  should  have  forgotten  to  mention  it.  The 
machinist  is  principally  occupied  in  observing  the  movements  of 
the  engine  as  a  whole,  receiving  and  making  reports,  regulating 
the  speed,  and  noting  data  in  the  log.  The  oilers  should  keep 
moving  about  that  part  of  the  machinery  under  their  care,  mak- 
ing systematic  inspection  of  all  bolts,  nuts,  keys,  set  screws,  stuf- 
fing boxes,  and  pipe  joints,  to  see  if  they  require  tightening,  also 
to  keep  a  lookout  for  any  indications  of  faulty  lubrication,  or 
heating  of  slides  or  journals,  applying  proper  remedies  when 
possible  and,  if  not,  reporting  the  fact  to  the  machinist  in  charge. 

The  oilers  must  also,  at  regular  intervals,  inspect  the  bilge 
strainers  and  gauge  glasses  on  separators  and  feed  tanks,  drain 
the  separators  when  necessary  and  notify  the  water  tender  if  the 
feed  tanks  are  too  full.  If  the  tanks  are  nearly  empty  he  fills 
them  by  salt  feed,  previously  consulting  the  water  tender  and 
machinist  with  regard  to  the  necessity. 

The  machinery  on  other  decks,  including  steering  engine,  are 
often  cared  for  by  one  of  the  engine-room  oilers. 

An  easy  method  of  cleaning  bilge  strainers  is  to  use  a  jet  of 
steam.  The  usual  method  is  to  put  the  strainer  in  an  ash  pit  and 
let  the  heat  melt  ofT  the  grease. 

The  oilers  must  keep  the  hand  rails  and  engine  wiped  ofi,  lad- 
ders and  platforms  swept,  and  see  that  everything  about  the  en- 
gine room  is  at  all  times  secured  for  sea,  collect  data  for  the 
log  and  give  it  to  the  machinist  at  the  end  of  every  hour.  He 
must  taste  the  water  in  the  hot  well  occasionally.  If  found  brack- 
ish, it  is  an  indication  that  the  hot  well  relief  valve  is  stuck  open 
or  that  the  condenser  tubes  leak.  A  slight  leak  in  two  or  three 
tubes  of  a  condenser  which  is  taking  all  the  steam  from  a  300 
H.  P.  engine  will  cause  a  brackish  taste  that  will  be  distinctly 
perceptible. 

All  use  of  oil  in  the  cylinders  must  be  avoided;  a  small  quan- 
tity of  cylinder  oil  being  applied  on  the  piston  rods  occasionally, 
if  no  oil  pipe  is  fitted  to  the  packing  box. 

The  number  of  wicks  in  a  cup  should  be  increased  or  dimin- 
ished as  occasion  requires  and  sight  feed  oil  cups  adjusted.  The 
wicks  should  be  taken  out,  dipped  in  oil,  and  replaced  from  time 


PROBLEMS,    NOTES    AND    SKETCHES.  II9 

to  time;  those  that  have  become  clogged  with  impurities  in  the 
oil  or  soaked  with  water  are  to  be  renewed,  taking  care  not  to  let 
them  get  twisted  or  extend  down  far  enough  to  touch  the  journal. 
Oil  which  accumulates  in  drip  pans,  under  journals  and  eccen- 
trics, must  be  removed  before  it  runs  over. 

Upon  entering  a  shallow,  muddy  harbor  or  river,  see  that  no 
sand  enters  the  water  service  pipes  and  gets  on  the  journals. 

Changing  Speed  at  Sea. 

When  manoeuvring  with  a  fleet,  keep  the  cut-offs  well  run  out; 
be  ready  to  let  live  steam  into  the  receivers  at  any  moment.  If 
required  to  increase  the  speed,  open  out  the  throttle  (or  run  out 
the  cut-off  further)  as  quickly  as  possible  without  causing  the 
index  of  the  steam  gauge  to  tremble.  Keep  the  water  tender 
informed  as  far  as  possible  in  advance  of  all  proposed  changes. 
If  the  change  is  to  be  permanent  (to  last  four  or  more  hours) 
notify  the  oilers  to  regulate  the  supply  of  oil.  After  the  cut-offs, 
pressure,  etc.,  are  altered  take  a  set  of  indicator  cards. 

Coming  into  Port. 

Upon  receiving  notice  that  the  ship  will  come  to  anchor  at  a 
given  time,  pass  the  word  to  the  water  tender,  and  also  call  down 
whatever  part  of  the  relief  watch  that  is  needed  to  bring  the  ship 
to  anchor;  and  get  the  capstan,  winch,  and  steam  launch  engines 
ready.  Make  an  inspection  of  all  machinery  in  operation  to  see 
if  the  reports  that  have  been  made  during  the  run,  of  repairs  re- 
quired, are  correct  and  complete. 

As  soon  as  the  engines  are  slowed,  shut  water  off  all  journals 
and  run  the  cut-offs  out  if  necessary  for  quick  handling  of  the 
engines. 

Arrival  in  Port. 

Upon  receiving  word  that  the  engines  will  no  longer  be  re- 
quired, notify  the  water  tender,  put  the  engines  in  the  position 
most  convenient  for  the  work  that  is  to  be  done  first,  to  save 
trouble  of  using  turning  engines;  shut  the  engine  stop  valves; 
open  drains  on  cylinders  and  valve  chests;  take  out  wicks;  empty 
and  clean  oil  cups,  scalding  the  latter  with  hot  water  and  a  little 
soda;  wash  out  all  oil  ways  in  crank  pin  journals  with  hot  water 


I20  MARINE    engines: 

and  syringe,  then  oil  the  journals;  clear  all  oil  cups  and  pipes 
about  engine;  stop  all  oil  pipes  and  cups  with  plugs  of  waste  if 
they  are  not  otherwise  covered;  cover  the  ends  of  journals  with 
gaskets  and  also  the  piston  rods,  pump  rods,  and  valve  stems, 
where  they  enter  the  stuffing  boxes.  Set  up  on  the  stern  tube 
stuffing  box  gland.  Clean  the  engine  frame  and  moving  parts 
while  the  grease  is  still  hot  and  soft.  The  air  and  circulating 
pumps  should  be  slowed  down,  but  not  stopped  until  the  steam 
pressure  in  the  fire  room  has  fallen  and  is  well  under  control. 
As  soon  as  the  pumps  can  be  stopped,  shut  the  outboard  valves. 
If  the  distiller  is  not  in  use,  start  it  up  to  make  use  of  the  steam 
in  the  main  boilers. 

When  cool  remove  the  man-hole  plates  from  the  cylinders,  and 
covers  or  sight  hole  plates  from  valve  chests.  Inspect  the  in- 
terior for  marks  of  cutting,  see  if  follower  bolts,  piston  nuts,  are 
loose,  etc. 

The  interior  of  a  cylinder  should  have  a  good  polish  all  over. 
If  there  is  a  dark  streak  in  a  longitudinal  direction  it  indicates 
that  the  springs  are  not  tight  at  that  part  of  the  piston.  The 
tightness  of  a  piston  may  be  tested  by  closing  one  end  of  the 
cylinder,  putting  the  link  in  mid  position  and  working  the  engine 
with  the  turning  engine.  A  candle  on  the  end  of  a  stick  being 
moved  around  the  circumference  of  the  piston  will  show  by  the 
flickering  flame  whether  much  air  leaks  past  as  the  piston 
approaches  the  closed  end  of  the  cylinder.  If  the  cylinder  is 
closed  at  both  ends  the  desired  information  is  obtained  by  ob- 
serving the  amount  of  air  pumped  in  and  out  the  indicator  pipes. 

After  inspection,  oil  the  interior  of  the  cylinder  and  wearing 
surface  of  valve  chests  with  cylinder  oil  and  replace  the  plates, 
taking  notice  that  the  openings  of  the  relief  valves  are  not  choked. 

Proceed  with  the  repairs  found  necessary  during  the  run,  be- 
ginning with  the  most  important  and  arranging  the  work  so  that 
the  dififerent  gangs  of  men  will  not  interfere  with  each  other; 
that  steam  will  not  be  shut  off  the  auxiliary  pipe  by  one  set,  just 
when  it  is  wanted  by  another;  that  floor  plates  will  not  be  taken 
up  in  a  passageway  where  there  will  be  much  passing  and  many 
other  like  considerations.     Repack  all  boxes  needing  it. 

In  case  there  are  no  repairs,  proceed  with  the  routine  inspec- 
tions of  various  parts  of  the  machinery  as  required  by  the  instruc- 
tions given  in  the  back  of  the  Steam  Log  Book.     Also  clean  out 


PROBLEMS,  NOTES  AND  SKETCHES.         -   121 

the  feed  tank  and  scale  evaporators  when  necessary.  Leaky 
condenser  tubes  are  located  by  filling  the  steam  space  with  water 
after  having  removed  the  bonnets  over  the  ends  of  the  tubes. 
Grease  may  be  melted  ofT  the  condenser  tubes  by  letting  in  steam 
after  draining  the  condenser,  taking  care  not  to  get  up  a  pres- 
sure in  the  condenser.  If  this  does  not  succeed,  fill  the  steam 
space  with  a  solution  of  lye,  soda  or  potash  in  fresh  water  and 
boil  by  admitting  a  jet  of  steam  in  the  bottom.  If  the  flat  rubber 
valves  used  in  many  air  pumps  are  curled  up,  they  must  be  turned, 
trimming  the  edges  if  found  to  have  swelled  and  overlapped  the 
valve  seat  too  far.     If  soft,  the  valves  must  be  renewed. 

It  is  customary  to  devote  the  morning  watch  to  cleaning  bright 
work,  working  all  levers,  valves,  cut-ofif  gear,  etc.,  about  the  de- 
partment. Iron  and  steel  are  cleaned  with  emery  cloth  and  oil, 
taking  care  to  rub  in  the  direction  in  which  the  piece  was  fin- 
ished by  the  manufacturer,  that  is  for  a  lever  of  flat  section  rub 
the  flat  sides  in  a  longitudinal  direction  and  the  round  handle  in 
a  plane  perpendicular  to  the  axis.  After  polishing,  such  pieces 
are  wiped  with  an  oily  rag  to  leave  a  very  thin  film  of  oil  on  the 
surface.  Brass  is  polished  with  Putz  pomade  or  else  with  finely 
ground  bath  brick  sifted  through  bunting.  Use  woolen  rags  for 
the  final  polish  and  leave  the  brass  as  dry  as  possible.  Soiled 
spots  on  the  paint  work  are  removed  by  washing  with  soap  and 
water  or  with  turpentine  on  a  rag.  Parts  of  the  engine  frames 
and  bulkheads  where  the  paint  is  blistered  or  peeled  are  washed 
with  lye  or  turpentine  and  repainted.  Bulkheads  and  other  paint 
work  are  scrubbed  with  soap  and  water.  Ladders  and  floor 
plates  are  scraped,  washed  with  lye,  dried  and  blackened  with 
plumbago  rubbed  on  with  a  brush,  using  very  little  plumbago  and 
rubbing  a  great  deal  or,  by  giving  a  coat  of  asphaltum  varnish. 
Hot,  dry  ashes  will  remove  grease  from  floor  plates.  Wooden 
lagging  is  scraped  and  rubbed  off  with  boiled  linseed  oil  and  a 
rag. 

The  main  engines  must  be  oiled  and  moved  about  one  turn  of 
the  crank  every  day,  taking  care  that  the  links  are  in  full  gear  at 
the  time  so  that  the  main  valves  will  be  moved  also. 

Auxiliary  engines  must  be  turned  every  day  and  be  worked 
periodically  as  often  as  found  necessary  by  experience:  those  on 
the  upper  decks  must  be  kept  well  drained  and  covered  up  in  cold 
weather  if  there  is  danger  of  freezing.     The  engine  room  bilges 


122  MARINE    ENGINES: 

must  be  cleaned  within  a  day  or  two  after  reaching  port  and  once 
a  week  after  that.  Oil  can  be  most  readily  removed  from  the 
bilges  by  using  scalding  water  from  the  boilers.  If  cold  water  is 
used,  caustic  potash,  or  better,  soda,  must  be  mixed  with  it  to 
form  a  strong  lye  which  is  applied  with  a  swab.  All  thick  de- 
posits must  first  have  been  scraped  away  and  taken  up. 

Disinfectants  are  not  to  be  used  instead  of  cleaning,  but  in  addi- 
tion to  it.  The  following  disinfectants  are  used:  llie  best  is 
that  prescribed  July  ii,  1883,  by  the  German  Government  for  use 
on  all  merchant  vessels,  viz.  hydrargyrum  bichloratum=bi- 
chloride  of  mercury:=corrosive  sublimate.  One  pound  is  dis- 
solved in  twenty  pounds  of  water  and  enough  of  this  solution 
used  so  that  there  shall  be  one  pound  of  the  sublimate  to  every 
half  ton  of  bilge  water.  In  a  pulverized  form  it  costs  about  one 
dollar  per  pound  but,  as  it  is  much  more  diluted  for  use  than  any 
other  disinfectant,  the  final  cost  will  not  be  much,  if  any,  greater^ 
It  is  a  deadly  poison  and  must  not  be  tasted  nor  allowed  to  get  in 
a  cut  or  sore.  Another  disinfectant  is  required  to  be  used  in  the 
German  navy,  viz.  chloride  of  zinc  used  in  a  diluted  state.  It  is 
not  so  efficacious  as  the  sublimate.  It  costs  about  fifty  cents  per 
pound.  Nitrate  of  lead  in  powdered  crystals  costs  about  twenty- 
five  cents  per  pound  and  is  very  efficacious.  It  should  be  diluted 
as  the  others,  for  a  disinfectant.  When  diluted  sufficiently  for 
the  purpose  for  which  it  is  used,  it  has  no  effect  whatever  in  the 
way  of  corroding  iron  as  may  easily  be  proved  by  trvdng  a  sample. 
A  piece  of  bright  iron  remained  bright  several  months  when  im- 
mersed in  such  a  solution.  The  two  latter  as  well  as  the  first  are 
deadly  poison  when  taken  internally  or  absorbed  through  cuts 
or  sores,  and  must  be  handled  accordingly. 

After  the  bilges,  come  the  double  bottom  compartments,  ob- 
serving the  same  precautions  prescribed  in  the  case  of  those  in 
the  fire  room.  While  in  port  a  fair  share  of  time  should  be  de- 
voted to  keeping  spare  parts  of  machinery,  tools,  etc.,  in  good 
condition. 

Ship  in  Dry  Dock. 

Under  these  circumstances,  the  first  work  to  be  done  is  the 
inspecting,  overhauling  and  repacking  of  all  sea  valves  and  clear- 
ing their  strainers,  renewing  zinc  protectors,  etc.,  taking  care  to 
not  remove  more  valves  in  a  day  than  can  be  replaced  before 


PROBLEMS,  NOTES  AND  SKETCHES.  1 23 

night,  as  required  by  the  regulations.  Also  inspect  the  interior 
of  the  pipes  as  far  as  possible  while  the  sea  valves  are  removed, 
and  note  any  pitting  or  deterioration  of  the  pipes. 

Inspect  the  propellers  and  see  that  all  bolts  are  tight.  Get  an 
accurate  measure  of  the  space  between  the  top  of  the  shaft  and 
the  top  of  the  stern  bearing  to  determine  how  much  the  bear- 
ings have  worn  down  and  record  it  in  the  log.  Remove  the  shaft 
coupling  bolts  of  the  coupling  nearest  the  engine  and  the  packing 
from  stern  tube  stuffing  box,  attach  a  lever  to  a  blade  of  the 
propeller,  then  suspend  weights  on  the  end  until  the  shaft  turns. 
Make  a  record  of  the  weights  and  length  of  lever.  By  comparing 
such  records,  any  increase  of  friction  due  to  the  shaft  being  out 
of  line  or  other  causes  will  be  discovered.  The  packing  in  the 
stern  tube  stuffing  box  must  always  be  inspected  by  removing  a 
few  turns  and  judging  from  them  whether  the  whole  amount 
needs  renewal. 


INDEX. 

ART.  PAGE. 

Ash-hoisting  engine,   Williamson's   29  84 

Ash-pit  closed,  Arrangement  for  forced  draught 3  16 

Baird's  distiller   31  90 

Blow  valve.  Surface  10  30 

Boiler,  Circulation  of  water  in   13  36 

launch,  Towne's     5  26 

Ward's     5  23 

Management  and  care  of  33  93 

Cavitation,  Investigation  of   21  63 

Theory   of    22  66 

Centrifugal  Steam  Separator,  DeRycke's 14  36 

Circulation  of  water  in  boilers   13  36 

Current,  Economical  speed  against  22  70 

Curve  of  Indicated  Thrust,  Completion  of  23  70 

DeLaval's  steam  turbine   21  59 

DeRycke's  centrifugal  steam  separator 14  36 

Dinkel's  steam  trap  15  37 

Distilling  apparatus  31  87 

Distiller,  Baird's  31  90 

Draught,  Forced,  with  closed  ash-pits 3  16 

Economical  speed  against  current  22  70 

Engine,  Williamson's  ash-hoisting   29  84 

Williamson's  Steam  Steering   30  86 

Management  and  care  of  34  no 

Engine,  and  auxiliaries.  Care  of 34  no 

Evaporator      31  90 

Evaporating  Plants,  IMultiple  efTect  32  92 

Evaporation,  Total  heat  of i  7 

Expansion  of  steam   17  39 

Forced  draught,  with  closed  ash-pits 3  16 

Fuel,  Liquid     4  19 

combined  with  coal  4  21 

Furnace,  Temperature  of i  11 

Gate  valve.  Chapman's 12  33 

Gauge,  Steam,  Lane's  improvement  on  Bourdon 8  ^ 

Heat  available  for  steam  generation   2  12 

Total,  of  evaporation  ■. . .     i  7 

Hydrokineter  13  36 

Hydrometer    11  31 


126  INDEX. 

ART.  PAGE. 

Indicated  thrust  curve,  Completion  of 23  70 

Indicator,  Steam  engine    24  71 

cards.  Method  of  taking  24  ^2 

Mean  effective  pressure  from  theoretical 25  73 

Water  accounted  for  by  26  78 

Water  accounted  for  by  2";  80 

Keyser's  Automatic  Water  Gauge  valves  9  29 

Lane's  improvement  on  Bourdon  gauge  8  28 

Liquid  fuel    4  19 

used  with  coal  4  21 

Macomb's  bilge  suction  pipe  strainer  28  83 

Management  of  boilers    Z2>  93 

engines  and  auxiliaries    34  no 

Mean  effective  pressure,  Calculation  of    17  39 

from  theoretical  card  25  73 

Parson's  steam  turbine    21  57 

Pressure,  Mean  effective,  of  an  expanding  gas 17  39 

Problems  on  total  heat  of  combustion  of  fuel,  air  supply,  etc. .. .  7 

heat  available  for  generating  steam 12 

efficiency  of  steam,  M.  E.  P.,  etc 43 

Zeuner  valve  diagram  52 

heat  lost  by  blowing  off 56 

commercial   horse-power    57 

comparative  data  of  vessels 69 

I.  H.  P.  from  theoretical  cards ^^ 

water  accounted  for  by  cards  81 

• 

Safety  valve 6  26 

Salinometer    11  31 

Saturation  of  water  in  boiler 11  31 

Sea  valves.  Method  of  securing 20  54 

Sentinel  valve   7  28 

Separator,  DeRycke's  centrifugal  steam  14  36 

Steam  gauge.  Lane's  improvement  on  Bourdon 8  28 

accoointed  for  by  indicator  card 26  78 

accounted  for  by  indicator  card 27  80 

Adiabatic  expansion  of   17  4i 

Isothermal  expansion  of   17  4i 

Expansion  of  saturated   17  4i 

Gain  by  expansion  of  17  39 

Gain  by  expansion  of  18  41 

Heat  available  for  generation  of  2  11 

engine  indicator   24  71 

required  per  I.  H.  P 16  38 

trap,    Dinkel's    I5  2>7 

turbine    21  57 


INDEX.  127 

ART.  PAGE. 

Steering  engine,  Williamson's  30  86 

Stop  valve,  Chapman's  gate  12  s;i 

Strainer  for  bilge  suction  pipe,  Macomb's 28  83 

Surface  blow  on  boilers 10  30 

Temperature  of  furnace  i  11 

Thrust  curve.  Completion  of  indicated 23  70 

Total  heat  of  evaporation  i  7 

Towne's  launch  boiler 5  26 

Trap,   Dinkel's  steam   15  37 

Turbine,  Parson's  steam   21  57 

DeLaval's   steam    21  59 

"  Turbinia  "    21  61 

Valve  diagram,  Zeuner's   19  46 

gate.   Chapman's    12  33 

Keyser's  automatic  water  gauge  9  29 

Safety 6  26 

Sea,  Method  of  securing 20  54 

Sentinel     7  28 

Surface  blow  10  30 

Ward's  launch  boiler  5  23 

Water  gauge  valve,  Keyser's  automatic 9  29 

circulation  in  boilers  13  36 

Williamson's  ash-hoisting   engine    29  84 

steam  steering  engine   30  86 

Zeuner's  valve  diagram  19  46 


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